Mozart Studies Online - This site by Hideo Noguchi has a good selection of Mozart works. Scroll down past the "Study Issues" to reach the clearly labeled MIDI files.

Mozart Piano Works - These Mozart piano sonatas were all sequenced by Marco Melanson.

ON Classical's Mozart MIDI files - An extensive collection of Mozart's works - excellent quality files. To download a file, simply click on the "MIDI" text next to the title of the work. A limit of five files per day may be downloaded for non-members. For 15 Euros (about $19.75 USD), you can have unlimited access to all the files on this enormous site, as well as download them all in a zip file for convenience.

The Classical Archives - Mozart - This website has changed extensively, but has a tremendous number of fantastic MIDI files. MIDI files are now all free downloads, but you must find the specific work you are looking for and download the MIDI as follows:

1. If you're not already a member (you can sign up for a free membership), click the "Become a member" link and enter your information.
2. Find the particular work you’re looking for (do NOT use "MIDI" in any searches).
3. Click the “MIDI” tab if there is one. If no "MIDI" tab is visible, then there are no MIDI files available for the work.
4. Click on the “XX Midis” text.
5. Click on the “Show sequences” text link to see the MIDI files that are available.
6. Click the Download (or Add to Downloads) and the file is put in a cart called “My Downloads”.
7. When you're done adding files (the MIDI files are free) to "My Downloads", click the "My Download button at the top of the page to go to your selected files and download them.