A young man who was raised on a farm and developed recurrent subcutaneous abscesses is described. Multiple cultures revealed either no growth or normal skin flora. Routine serologic evaluation for Brucella agglutinins was negative, including serial dilution to greater than 1:1,000 of the patient's sera. Brucella abortus infection was documented by the use of a binding antibody assay to measure the patient's class-specific serologic response and obtaining a positive culture by incorporating methicillin into the culture media to suppress overgrowth of staphylococci. Thus, the potential difficulty in making the diagnosis of brucellosis is demonstrated, and the use of extraordinary means, namely, specific selective media and a binding antibody assay, to make the diagnosis is emphasized.