Six weimaraner puppies, five of which were genetically related, showed systemic signs associated with hypertrophic osteodystrophy, including fever and involvement of the gastrointestinal, respiratory or nervous systems, in addition to the metaphyseal lesions. In five of the dogs the clinical signs developed less than 10 days after they had been vaccinated with a modified live virus vaccine. Radiographic findings suggested that both the hindlimbs and forelimbs were equally involved in the disease process. Abnormal haematological findings included leucocytosis with neutrophilia and monocytosis, and there was a consistent increase in the activity of alkaline phosphatase. Serum protein electrophoretic studies of three of the dogs revealed hypogammaglobulinaemia and abetaglobulinaemia in two of them. Conservative treatment with rest and non-steroidal anti-inflammatory drugs had little effect, and treatment with corticosteroids appeared to give the best results.