ABSTRACTA clinical trial was conducted to evaluate the efficacy of a 1 per cent pimaricin suspension in the treatment of canine otitis externa associated with Malassezia pachydermatis. Of 40 dogs examined, M pachydermatis was the sole infection in five ears and was commensal with other organisms in 35 ears. Pimaricin in a 1 per cent suspension was administered twice a day for two weeks. Employing continuous therapy, signs accompanying otitis externa were ameliorated steadily, and satisfactory results were achieved in 33 of the dogs. No noticeable side effects were observed with the pimaricin suspension.