A 2-year-old female Moluccan cockatoo (Cacatua moluccensis) was presented with a 20-month history of chronic malodorous diarrhea. Megacloaca with cloacitis, suspected clostridial enteritis, and suspected chronic synsacral and caudal vertebral osteomyelitis were diagnosed on the basis of radiograph results, laboratory testing, radiographic and fluoroscopic gastrointestinal contrast studies, and histopathologic examination of cloacal tissue biopsy samples. The bird was treated surgically by reducing the coprodeum. In addition, aggressive medical care, including fluids, nutritional support, and antibiotics, was instituted. Although results of clostridial toxin enzyme immunoassays and fecal clostridial cultures were negative, we suspected clostridial overgrowth because of the bacterial morphology on a Gram's stain of fecal samples. At the time of this report (4 years after surgery), the cockatoo remains relatively asymptomatic. Attempts to discontinue metronidazole therapy or lactobacillus supplementation result in recurrence of malodorous feces and retention of feces within the coprodeum. The cause of the megacloaca was never definitively established; however, surgical reduction of the coprodeum appears to have improved the bird's quality of life and possibly reduced the potential for future health complications.