The authors present the results of a study designed to measure the relative effectiveness of chloramphenicol, chlortetracycline (Aureomycin), oxytetracycline (Terramycin), and sulfadiazine in the treatment of lymphogranuloma venereum. The responses of the drug-treated patients are compared with those of a control group of patients who received symptomatic treatment only. The effectiveness of each method of treatment is evaluated in terms of the time required for resolution of the bubo and the rate of decline in the amount of complement-fixing antibody.