# Opening a DICOMDIR? Choose the whole disc instead

> DICOMDIR is a disc's table of contents, not the images. Choose the whole disc or folder and MesDICOM opens the images it lists. Free, in your browser.

DICOMDIR is the disc's table of contents, not your images. Choose the disc or the folder that holds DICOMDIR, and MesDICOM opens the images themselves — in your browser, free, nothing uploaded.

Open your scans here: https://mesdicom.com/dicomdir-viewer/ — or at https://mesdicom.com/

You can't open a DICOMDIR file by itself, because it holds no images — it is a list of where the images are. Choose the disc, or the folder that contains DICOMDIR, with **Open a disc or folder…** above. MesDICOM reads the image files themselves and opens your study.

## What is a DICOMDIR file?

DICOMDIR is the index the DICOM standard puts at the top of a disc or USB drive. It lists the patients, studies, series and images on the media and where each image file sits. The images are separate files, usually in a folder named DICOM, often with names like `IM000001` and no extension.

That is why opening DICOMDIR in a viewer that expects images shows nothing, or an error: there are no pixels in it.

## How do I open a disc that has a DICOMDIR?

1. Insert the disc or USB drive. If a viewer program starts, close it.
2. Click **Open a disc or folder…** and choose the drive itself, or the folder that holds DICOMDIR.
3. MesDICOM reads every file, keeps the DICOM images, and sorts them into studies and series.

If the disc holds more than one study, you choose which to open. The full walk-through, including what to do when the browser won't offer the drive, is in [opening a CT or MRI disc](https://mesdicom.com/open-dicom-cd/).

## What happens if I pick only DICOMDIR?

MesDICOM recognises it and says so: this is the disc's index, not the images. It offers **Open a disc or folder…** so you can choose the folder that holds DICOMDIR, and the images come with it.

## Does it work with a copy of the disc?

Yes. A copy on your computer, a USB stick or a shared drive opens the same way, as long as you copy the whole disc — the image folders matter, DICOMDIR itself is optional. A ZIP of the disc opens too, with **Open files or a ZIP…**.

## Which images open?

CT, MR, X-ray, ultrasound and other DICOM images, single images and multi-frame series, in the common uncompressed and compressed formats (JPEG, JPEG Lossless, JPEG-LS, JPEG 2000 and RLE).

MesDICOM shows the images; it doesn't interpret them.

## Questions

### Can MesDICOM open a DICOMDIR file?

It opens the images a DICOMDIR belongs with. Choose the disc or the folder that holds DICOMDIR with **Open a disc or folder…**. If you pick DICOMDIR on its own, MesDICOM tells you it is the index and offers to choose the folder instead.

### The image files have no .dcm extension. Will they open?

Yes. MesDICOM recognises DICOM files by what is inside them, not by their names, so files called IM000001 or with no extension at all open normally.

### Do I need DICOMDIR to open the images?

No. A folder of DICOM files opens with or without it.

### What if the folder holds files that aren't images?

They are skipped. MesDICOM keeps the DICOM images and leaves out the viewer program, autorun files and documents.

## Related guides

- [Open a CT or MRI disc](https://mesdicom.com/open-dicom-cd/index.html.md): Got your scan on a CD or DVD from the hospital? Open the DICOM images in your browser on Windows or Mac. No viewer program, no upload, free.
- [Open a DICOM ZIP](https://mesdicom.com/open-dicom-zip/index.html.md): Got your scan as a ZIP by email, WhatsApp or a hospital download link? Open it in your browser without unzipping. Works on computers and phones. Free.
- [CT scan viewer](https://mesdicom.com/ct-scan-viewer/index.html.md): Open your CT scan in your browser: lung, bone and soft-tissue windows, three planes, 3D and measurements. From a disc, folder or ZIP. Free, nothing uploaded.

Updated October 24, 2026. For viewing and reference only — not intended for diagnosis or treatment decisions.