We have examined the incidence of new antioxidant compounds, so-called lazaroids, on the morphological and biochemical aspects of differentiation of C2 mouse skeletal muscle cells. We show that three lazaroids (U-74006F, U-74389F and U-83836E) enhance fusion of myogenic cells when added at the day of fusion. A parallel increase in nicotinic acetylcholine receptor expression and skeletal muscle alpha-actin content was observed. This promoting effect of lazaroids on myogenesis could be related to inhibition of free radical-mediated muscle damage. Therefore, one could expect that lazaroids might be useful in the treatment of degenerating muscle diseases such as Duchenne muscular dystrophy.