Purified rabbit skeletal muscle myosin in 0.6M KCl was deposited onto mica flakes, quick-frozen by contact with a liquid helium- cooled copper block in a Heuser-type cryopress, and freeze-etched in a Balzers 400 freeze fracture machine. The sample was then rotary-replicated with Pt-C at 11 degrees and visualized in a JEOL 100CX2 transmission electron microscope at 100 kev. Images were recorded on Kodak 4489 film at 100,000x magnification. Stereo pairs were taken at +5 and -5 degrees. Films were scanned with a 20 micrometer pixel spacing on a Nikon Coolscan 9000ED. Note the classic appearance of the individual molecules with two globular heads (myosin subfragment 1) and the long rod-like tail. LEFT image of a stereo pair.