Treatment failures with standard doses of penicillin have been observed in the Sexually Transmitted Diseases (STD) clinics in Trinidad and Tobago. In the absence of an ongoing surveillance system, the antimicrobial susceptibility of 518 Neisseria gonorrhoeae strains was determined in order to guide treatment. 39 (7.6%) strains were resistant to penicillin, including 27 (5.2%) positive for beta-lactamase; that is penicillinase-producing Neisseria gonorrhoeae (PPNG). 51 (10%) strains were resistant to tetracycline, with 26 (5.0%) of these exhibiting high levels of resistance compatible with tetracycline resistant Neisseria gonorrhoeae (TRNG). Six strains showed evidence of having both PPNG and TRNG plasmids, and five strains showed chromosomally-mediated resistance to both penicillin and tetracycline. The overall resistance rate to penicillin and tetracycline was 17.7%. There was no resistance to spectinomycin, cefuroxime, ceftriaxone and norfloxacin. The resistance rates demonstrated in this study are sufficiently significant to preclude the use of penicillin and tetracycline in the STD clinics and to justify the use of newer antimicrobials. It is essential that resistance patterns be monitored by continued surveillance.