In 1991, a mass stranding of short-finned pilot whales (Globicephala macrorhynchus) occurred near Key West, Florida. Six of these whales were airlifted to the quarantine marine mammal pool at The Miami Seaquarium. The whales were dehydrated, sunburned, and four had a moderate leukocytosis with an absolute mature neutrophilia and absolute lymphopenia and eosinopenia. Within 24 hours all the whales developed unilateral peduncular rhabdomyolysis and scoliosis that responded to neuromuscular electrostimulation physical therapy. Intensive therapy was instituted by animal care personnel and trainers following standard quarantine procedures. Within a six week period after the whales arrived, a long-finned pilot whale (Globicephala melas), common dolphin (Delphinus delphis), and Pacific bottlenose dolphin (Tursiops truncatus gilli) died acutely from either acute hemorrhagic pneumonia or suppurative bronchointerstitial pneumonia. All had a profound absolute leukopenia. Within the same period, four Atlantic bottlenose dolphins (Tursiops truncatus) housed in the same habitat developed coarse dry non-productive coughs. Clinicopathologic data indicated a nonspecific moderate leukocytosis with mature absolute neutrophilia and absolute lymphopenia. Microbiologic blowhole cultures yielded pure Pseudomonas aeruginosa. Systemic antibiotic and antifungal therapy were instituted after two cases developed secondary aspergillosis. All died after generally a long protracted pulmonary illness with histopathologic lesions consistent with morbillivirus bronchointerstitial pneumonia and secondary immunologic compromise. Retrospective studies indicated serologic evidence of dolphin morbillivirus infection in 3 of the stranded pilot whales with seroconversion occurring in 1 whale while in the park. Morbillivirus seroconversion occurred in 3 of the bottlenose dolphins that died after the pilot whales arrived at the aquarium. There was also serologic evidence of dolphin morbillivirus infection in 1 bottlenose dolphin that remained asymptomatic and lived. Polymerase chain reaction methodology is now being implemented using tissues to demonstrate morbillivirus infection. While strongly circumstantial, the potential for stranded cetaceans acting as vectors of infection for animals maintained at oceanaria cannot be overlooked, especially with the emergence of new infectious viral agents.