During the 10-year period from 1980 through 1989 using gonococci isolated in Sapporo, we studied beta-lactamase production capacity and the sensitivity of various antibacterial agents and obtained the following results. 1. The frequency of isolating beta-lactamase producing gonococci (PPNG) displayed a gradual tendency to increase during the first half of the 80's and reached a peak in 1985 of 23.9% (61/255). However, thereafter it tended to decline and in 1989 it was 6.3% (2/32). 2. The sensitivity to penicillin-type antibacterial agents was higher against PPNG than non-PPNG against PCG, ABPC, and AMPC displaying about a 7 level MIC90 so that it was quite sensitive. Against CVA/AMPC, SBTPC it showed a relatively favorable MIC90. Also, the sensitivity of PPNG against AMPC with 1984 as the boundary, thereafter the MIC distribution was observed to decline somewhat. 3. Against the monobactam-type injectable drug, AZT, both non-PPNG and PPNG showed a low MIC distribution and against SPCM both showed a relatively high MIC distribution of 3.13-25 micrograms/ml. 4. In regard to the sensitivity to cephem-type antibacterial agents, against such 3rd generation injectables as CZX, CFTM-PI, etc. it displayed a particularly low MIC distribution. 5. Against tetracycline and macrolide antibacterial agents, it displayed a relatively high MIC distribution. 6. Against new quinolone type antibacterial agents, regardless of being non-PPNG or PPNG, it showed a low MIC.