This study by one individual of 1,200 patients with cat-scratch disease provides a heretofore unavailable realistic evaluation of a common infectious disease. All patients had lymphadenopathy, a prerequisite for diagnosis. Suppuration occurred in 11.8% of patients. Cat contact was established for 99.1%, and the cat was immature in the vast majority. An inoculation site, the most neglected feature in the study of the patients, was detected in 92.6%. The results of a skin test, considered as specific as the standard tuberculin test and to be safe but not standardized, was positive in 99%. The 12 patients with negative skin tests probably were tested too early in the course of the disease to have developed reactivity. Skin tests of 578 family members of patients, who served as controls, gave positive results in 18.5%. Of 60 patients with unusual manifestations, 48 had the oculoglandular syndrome of Parinaud. Other manifestations included erythema nodosum, encephalopathy, osteolytic lesions, thrombocytopenic purpura, and erythema marginatum. Most patients in this series had received antibiotics of many types during the course of the disease. None appeared beneficial. The disease is benign in character in a majority of patients. Surgical removal of involved lymph nodes or biopsy of lymph nodes or inoculation sites is not necessary for diagnosis or management. A survey of hospitals in the United States discharging more than 750 pediatric patients annually indicates that cat-scratch disease is a problem in all sections of the country.