diff --git a/README.md b/README.md
index 335011e..61fcef6 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,9 @@ TRX-Python provides a unified CLI (`trx`) for common operations:
 # Show all available commands
 trx --help
 
+# Display TRX file information (header, groups, data keys, archive contents)
+trx info data.trx
+
 # Convert between formats
 trx convert input.trk output.trx
 
@@ -60,6 +63,7 @@ trx validate data.trx
 Individual commands are also available for backward compatibility:
 
 ```bash
+trx_info data.trx
 trx_convert_tractogram input.trk output.trx
 trx_concatenate_tractograms tract1.trx tract2.trx merged.trx
 trx_validate data.trx
diff --git a/pyproject.toml b/pyproject.toml
index 2f6f606..360cd70 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -80,6 +80,7 @@ trx_simple_compare = "trx.cli:compare_cmd"
 trx_validate = "trx.cli:validate_cmd"
 trx_verify_header_compatibility = "trx.cli:verify_header_cmd"
 trx_visualize_overlap = "trx.cli:visualize_cmd"
+trx_info = "trx.cli:info_cmd"
 
 [tool.setuptools]
 packages = ["trx"]
diff --git a/trx/cli.py b/trx/cli.py
index 92202a6..afb2c15 100644
--- a/trx/cli.py
+++ b/trx/cli.py
@@ -13,7 +13,7 @@
 from typing_extensions import Annotated
 
 from trx.io import load, save
-from trx.trx_file_memmap import TrxFile, concatenate
+from trx.trx_file_memmap import TrxFile, concatenate, load as load_trx
 from trx.workflows import (
     convert_dsi_studio,
     convert_tractogram,
@@ -874,6 +874,111 @@ def visualize(
     )
 
 
+def _format_size(size_bytes: int) -> str:
+    """Format byte size to human readable string.
+
+    Parameters
+    ----------
+    size_bytes : int
+        Size in bytes.
+
+    Returns
+    -------
+    str
+        Human readable size string (e.g., "1.5 MB").
+    """
+    for unit in ["B", "KB", "MB", "GB"]:
+        if size_bytes < 1024:
+            return f"{size_bytes:.1f} {unit}" if unit != "B" else f"{size_bytes} {unit}"
+        size_bytes /= 1024
+    return f"{size_bytes:.1f} TB"
+
+
+@app.command("info")
+def info(
+    in_tractogram: Annotated[
+        Path,
+        typer.Argument(help="Input TRX file."),
+    ],
+) -> None:
+    """Display detailed information about a TRX file.
+
+    Shows file size, compression status, header metadata (affine, dimensions,
+    voxel sizes), streamline/vertex counts, data keys (dpv, dps, dpg), groups,
+    and archive contents listing similar to ``unzip -l``.
+
+    Parameters
+    ----------
+    in_tractogram : Path
+        Input TRX file (.trx extension required).
+
+    Returns
+    -------
+    None
+        Prints TRX file information to stdout.
+
+    Examples
+    --------
+    $ trx info tractogram.trx
+    $ trx_info tractogram.trx
+    """
+    import zipfile
+
+    if not in_tractogram.exists():
+        typer.echo(
+            typer.style(f"Error: {in_tractogram} does not exist.", fg=typer.colors.RED),
+            err=True,
+        )
+        raise typer.Exit(code=1)
+
+    if in_tractogram.suffix.lower() != ".trx":
+        typer.echo(
+            typer.style(
+                f"Error: {in_tractogram.name} is not a TRX file. "
+                "Only .trx files are supported.",
+                fg=typer.colors.RED,
+            ),
+            err=True,
+        )
+        raise typer.Exit(code=1)
+
+    # Show archive info
+    file_size = in_tractogram.stat().st_size
+    typer.echo(f"File: {in_tractogram}")
+    typer.echo(f"Size: {_format_size(file_size)}")
+
+    with zipfile.ZipFile(str(in_tractogram), "r") as zf:
+        total_uncompressed = sum(info.file_size for info in zf.infolist())
+        is_compressed = any(info.compress_type != 0 for info in zf.infolist())
+        typer.echo(f"Entries: {len(zf.infolist())}")
+        typer.echo(f"Compressed: {'Yes' if is_compressed else 'No'}")
+        typer.echo(f"Uncompressed size: {_format_size(total_uncompressed)}")
+
+    typer.echo("")
+
+    # Show TRX content info
+    trx = load_trx(str(in_tractogram))
+    typer.echo(trx)
+
+    # Show file listing (unzip -l style)
+    typer.echo("\nArchive contents:")
+    typer.echo("  Length      Date    Time    Name")
+    typer.echo("---------  ---------- -----   ----")
+    with zipfile.ZipFile(str(in_tractogram), "r") as zf:
+        for zinfo in zf.infolist():
+            dt = zinfo.date_time
+            date_str = f"{dt[1]:02d}-{dt[2]:02d}-{dt[0]}"
+            time_str = f"{dt[3]:02d}:{dt[4]:02d}"
+            typer.echo(
+                f"{zinfo.file_size:>9}  {date_str} {time_str}   {zinfo.filename}"
+            )
+        num_files = len(zf.infolist())
+        typer.echo("---------                     -------")
+        typer.echo(f"{total_uncompressed:>9}                     {num_files} files")
+
+    trx.close()
+
+
 def main():
     """Entry point for the TRX CLI."""
     app()
@@ -964,6 +1069,12 @@ def _create_standalone_app(command_func, name: str, help_text: str):
     "Display tractogram and density map with bounding box.",
 )
 
+info_cmd = _create_standalone_app(
+    info,
+    "trx_info",
+    "Display information about a TRX file.",
+)
+
 
 if __name__ == "__main__":
     main()
diff --git a/trx/tests/test_cli.py b/trx/tests/test_cli.py
index ddb70bd..35b78d3 100644
--- a/trx/tests/test_cli.py
+++ b/trx/tests/test_cli.py
@@ -27,7 +27,10 @@
 )
 
 # If they already exist, this only takes 5 seconds (check md5sum)
-fetch_data(get_testing_files_dict(), keys=["DSI.zip", "trx_from_scratch.zip"])
+fetch_data(
+    get_testing_files_dict(),
+    keys=["DSI.zip", "trx_from_scratch.zip", "gold_standard.zip"],
+)
 
 
 def _normalize_dtype_dict(dtype_dict):
@@ -91,6 +94,10 @@ def test_help_option_visualize(self, script_runner):
         ret = script_runner.run(["trx_visualize_overlap", "--help"])
         assert ret.success
 
+    def test_help_option_info(self, script_runner):
+        ret = script_runner.run(["trx_info", "--help"])
+        assert ret.success
+
 
 # Tests for unified trx CLI
 class TestUnifiedCLI:
@@ -136,6 +143,35 @@ def test_trx_visualize_help(self, script_runner):
         ret = script_runner.run(["trx", "visualize", "--help"])
         assert ret.success
 
+    def test_trx_info_help(self, script_runner):
+        ret = script_runner.run(["trx", "info", "--help"])
+        assert ret.success
+
+    def test_trx_info_execution(self, script_runner):
+        """Test trx info command execution on a real TRX file."""
+        trx_path = os.path.join(get_home(), "gold_standard", "gs.trx")
+        ret = script_runner.run(["trx", "info", trx_path])
+        assert ret.success
+        # Check key output elements
+        assert "VOXEL_TO_RASMM" in ret.stdout
+        assert "DIMENSIONS" in ret.stdout
+        assert "streamline_count" in ret.stdout
+        assert "vertex_count" in ret.stdout
+        assert "Archive contents:" in ret.stdout
+
+    def test_trx_info_wrong_extension(self, script_runner):
+        """Test trx info rejects non-TRX files."""
+        tck_path = os.path.join(get_home(), "gold_standard", "gs.tck")
+        ret = script_runner.run(["trx", "info", tck_path])
+        assert not ret.success
+        assert "not a TRX file" in ret.stderr
+
+    def test_trx_info_file_not_found(self, script_runner):
+        """Test trx info handles missing files."""
+        ret = script_runner.run(["trx", "info", "nonexistent.trx"])
+        assert not ret.success
+        assert "does not exist" in ret.stderr
+
 
 # Tests for workflow functions
 class TestWorkflowFunctions: