Neisseria gonorrhoeae isolates that were resistant to ciprofloxacin and/or penicillin were analysed to investigate the escalating problem of antibiotic-resistant gonorrhoea in the north east of England. Opa-typing (outer membrane opacity protein) was carried out on isolates resistant to ciprofloxacin and of nutrient nonrequiring (NR) auxotype. In the year 2000 there were 265 cases of gonorrhoea, of which 44 (16.6%) were resistant to penicillin and 12 (4.5%) were resistant or had reduced sensitivity to ciprofloxacin (with only four of these acquired outside the UK). Three (7.5%) of the non-beta-lactamase penicillin-resistant isolates were imported from abroad. By Opa-typing of ciprofloxacin-resistant strains, one pair of the isolates was similar, two were unique and one was similar to the Oldham/Rochdale outbreak strain described early in 2000. This marked increase in the prevalence of indigenous ciprofloxacin resistance requires continued surveillance and may soon necessitate an alteration in our first line treatment.