A pied imperial pigeon (Ducula bicolor bicolor) presented weak and unable to fly. Results of a complete blood count and plasma biochemical analysis revealed a leukocytosis and elevations in multiple enzymes, respectively. Sarcocystosis was suspected and was definitively diagnosed from muscle biopsy samples. A multidrug treatment regimen consisting of diclazuril, pyrimethamine, and trimethoprim-sulfamethoxazole was instituted. Muscle biopsies collected after 40 days of treatment were normal. The bird died of a bacterial septicemia 18 months after treatment with no evidence of sarcocystosis. This case suggests that diclazuril may be a useful drug in the treatment of avian sarcocystosis.