Isozyme patterns of cholinesterase (ChE) from heart, tongue, and skeletal muscle of normal and dystrophic hamsters are presented. Two principal bands, bands 1 and 2, were evaluated. Band 1 migrates faster towards the anode than does band 2. While bands 1 and 2 stain for AChE and were found in control muscles, only band 2 was stained by a pseudocholinesterase (BuChE) and was decreased in samples from dystrophic hamsters. The decrease in BuChE was most pronounced in dystrophic heart muscle. The low level of BuChE measured for dystrophic animal tissue was similar to isozyme patterns found in embryonic tissue and in denervated muscle. BuChE obtained by acrylamide gel electrophoresis along with 16S AchE appears to be a useful biochemical marker of nerve-muscle interactions.