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Extracts of penicillinase-producing strains of Neisseria gonorrhoeae obtained from several localities in Southeast Asia exhibited similar patterns of relative rates of hydrolysis of benzylpenicillin, ampicillin, carbenicillin, and cephaloridine. Methicillin and oxacillin were not hydrolyzed. The isoelectric point of the beta-lactamase from these strains was 5.38 +/- 0.05, and the molecular weight was approximately 22.5. These properties, as well as the Km values determined for a range of substrates, were the same for the enzyme purified from one of the strains. These observations are consistent with those reported for other gonococcal beta-lactamases of the TEM-1 type. Cefamandole and to a lesser extent, cefoperazone, were also hydrolyzed by these extracts; however, the newer beta-lactam antibiotics piperacillin, cefuroxime, cefoxitin, ceftriaxone, ceftazidime, and moxalactam were stable. These stable compounds had little inhibitory effect on the activity of the enzyme toward benzylpenicillin or cephaloridine.