we studied the effect of pulsed ultrasound therapy (ust) and antibothropic polyvalent antivenom (pav) on the regeneration of mouse extensor digitorum longus muscle following damage by bothrops jararacussu venom. animals (swiss male and female mice weighing 25.0 ± 5.0 g; 5 animals per group) received a perimuscular injection of venom (1 mg/kg) and treatment with ust was started 1 h later (1 min/day, 3 mhz, 0.3 w/cm2, pulsed mode). three and 28 days after injection, muscles were dissected and processed for light microscopy. the venom caused complete degeneration of muscle fibers. ust alone and combined with pav (1.0 ml/kg) partially protected these fibers, whereas muscles receiving no treatment showed disorganized fascicules and fibers with reduced diameter. treatment with ust and pav decreased the effects of the venom on creatine kinase content and motor activity (approximately 75 and 48%, respectively). sonication of the venom solution immediately before application decreased the in vivo and ex vivo myotoxic activities (approximately 60 and 50%, respectively). the present data show that ust counteracts some effects of b. jararacussu venom, causing structural and functional improvement of the regenerated muscle after venom injury.