Absorption of amoxicillin after oral administration has previously been shown to be superior to that of ampicillin. A single 3.5-g dose of ampicillin taken orally with 1 g of probenecid is an effective regimen for the treatment of gonorrhea. In this study in normal adult volunteers, two regimens of smaller doses of amoxicillin (2.0 g with 500 mg of probenecid, and 3.0 g without probenecid) gave peak serum levels of antibiotic equivalent to those reported for the ampicillin-probenecid regimen. Based on these pharmacologic studies, both amoxicillin regimens are acceptable for further clinical evaluation as alternatives to ampicillin-probenecid in the therapy of gonococcal infection.