Minimum inhibitory concentrations of penicillin and eight cephalosporins were determined on solid media for fresh isolates of Neisseria gonorrhoeae. Against penicillin-sensitive strains, the order of activity was cefuroxime (which was as active weight-for-weight as benzylpenicillin), cefamandole, cefoxitin, cephalothin, cefazolin, cephradine, cephalexin and cephaloridine. Some of the agents, notably cefoxitin, cephaloridine, cefuroxime and cefazolin, were relatively more active against penicillin-insensitive strains, for which the order of effectiveness was cefuroxime (which was as active as ampicillin), cefoxitin, cefazohin, cefamandole, cephalothin, cephaloridine, cephalexin, and cephradine. Clinical trials of cefuroxime, cefoxitin, cefazohin and cefamandole might be worthwhile.