Eight patients with Legionnaires' disease were seen at one hospital in the summer of 1979. They presented in the same 12-day period with an illness of rapid onset characterized by fever, chills, malaise, profuse sweating and neurologic symptoms. Neutrophilia, a high erythrocyte sedimentation rate, proteinuria, hypoalbuminemia, hyponatremia, hypochloremia and abnormal liver enzyme levels in the serum were usually noted. The roentgenographic findings in the lungs ranged from segmental interstitial infiltration to panlobar pneumonia. Seven patients responded to erythromycin treatment, though one died suddenly, presumably of unrelated cardiac disease. The other patient died of a combination of renal and respiratory failure, with pulmonary edema.