The diagnosis of chronic brucellosis often is uncertain because of lack of cultural proof. Bacteremia seldom is present in the ambulatory patient with low grade fever. However, there is strong presumptive clinical and laboratory evidence that this type of Brucella infection exists in large numbers of patients. Because of the uncertainty of diagnosis and the frequently relapsing course of the disease, evaluation of therapeutic methods is difficult. The availability of apparently nontoxic antibiotics, presumably effective when given orally, allowed treatment of ambulatory patients without the economic loss incident to interruption of work or hospital care. Brucella antigen therapy had been shown to bring about recovery in 50 to 80 per cent of patients in this category1but was not necessarily curative. Treatment with streptomycin and sulfadiazine, given simultaneously,2apparently is capable of bringing about actual cure but requires hospital care or extremely close supervision and may result in