A total of 12 Beagle dogs were randomly distributed into two groups of 3 animals/sex/group. The test material, triphenylphosphine (TPP), was admini- stered to Group II animals by gastric.intubation at a dose level of 25 mg/kg/day for 21 consecutive days. The Group I (vehicle control) animals received the equivalent awount of corn oil alone. Following the 3 week dosing period, all animals were observed for an additional 4 weeks prior to sacrifice. The administration of TPP did not significantly affect body weight or food consumption. However, 3 out of the 6 animals in Group II exhibited signs of neurological impairment. The signs were first evident approximately 14 days following initiation of TPP treatment and were characterized principally by ataxia and hindlimb weakness. There was a slight improvement noted in the affected animals following cessation of compound administration. Thereafter, no further improvement was noted. No such effects were observed in the vehicle control group. Complete gross postmortem examinations were performed on all animals after 7 weeks. No compound-related effects were observed.