Eight wild-caught juvenile American alligators (Alligator mississippiensis) were given diazepam (0.4 mg/kg i.m.) and atracurium (4 mg/kg i.m.) in one trial and tiletamine-zolazepam (15 mg/kg i.m.) in another trial to describe the effects and to evaluate the potential of these drugs in the chemical restraint of crocodilians. Atracurium resulted in profound immobilization, with loss of the righting reflex at 38.8 +/- 23.4 (mean +/- SD) min postinjection (PI). Recovery of the righting response occurred at 316.9 +/- 36.2 min PI. Five of the eight alligators became apneic. Apnea occurred at 28.0 +/- 16.4 min after loss of the righting reflex and persisted for 271.0 +/- 159.0 min. Resumption of spontaneous ventilation was variable, ranging from 205 min before to 195 min after recovery of the righting reflex. Temperature and heart rate were not significantly changed from baseline by atracurium. Tiletamine-zolazepam administration did not completely abolish the righting reflex, but righting was slowed in all animals by 15 min PI. Normal righting was recovered at 183.8 +/- 33.8 min PI. Peak effect, as measured by slowest righting, occurred at at 52.5 +/- 31.0 min PI. Temperature, heart rate, and respiratory rate were not significantly altered by tiletamine-zolazepam. The alligators injected with tiletamine-zolazepam were sluggish, nonaggressive, and unable to rise. Chemical restraint of alligators by tiletamine-zolazepam is sufficient for capture, translocation, and minor medical procedures. The prolonged apnea induced by atracurium is undesirable and makes this drug unsuitable for chemical restraint of American alligators.