A review of the susceptibility of Neisseria gonorrhoeae isolated from 4415 episodes of infection in Scotland between 1991 and 1999 showed that the proportion of isolates with lowered susceptibility (ciprofloxacin minimum inhibitory concentration [MIC] > or = 0.05 mg/L) increased from 0.5% in 1991 to 5% in 1999 (p<0.001), whereas the proportion of isolates with clinical resistance (ciprofloxacin MIC > or = 1 mg/L) was significantly higher in 1999 than the average for the preceding 4 years (2.2% vs 0.9%; p=0.02). Ciprofloxacin is a recommended treatment for gonococcal infection in the UK but if resistance continues to increase at the present rate it might not be suitable as a first-line treatment of gonorrhoea for much longer.