A novel magnetic disc recording cassette is provided as a thin polygonal cassette housing containing a disc of flexible magnetic recording media. A drive hub attached to the media is exposed through the cassette and cooperates with a complementary drive hub in a deck which receives the cassette in slot-loading fashion into a carriage which in turn positions the cassette for driving of the recording disc. The cassette and disc may be single or double sided, and includes access opening for a magnetic transducer to follow different circular tracks, or a helical track. The thin magnetic disc is provided with backing in the cassette to assure compliant interface of the transducer with the magnetic recording disc. The backing may be a backing sheet, discs of backing material, or felt surfaced shims adjacent the region of interface with the transducer. Passages are provided for air flow in response to rotation of the recording disc to provide a continuing smooth and minimum friction rotation of the disc within the cassette. The cassette is supported either on the base of the carriage or by a separately adjustable three point suspension system.