The auxotype, serogroup and antimicrobial susceptibility of 977 clinical isolates of Neisseria gonorrhoeae obtained at St Thomas' Hospital, London, during 1989 were determined; 23 isolates from 15 patients were resistant to 4-quinolones. Twelve of the patients acquired their infection in the UK and these strains were generally sensitive to other antimicrobial agents; strains from 10 patients were of serogroup IB-6. Three patients acquired their strains outside the UK and these isolates were multi-resistant and of different serogroups.