As few studies have compared the clinical features of rectal gonorrhoea in men who have sex with men with or without concurrent chlamydial infection, this longitudinal study was undertaken to address this issue. The cohort consisted of 129 men with rectal gonorrhoea, 34 of whom had concurrent chlamydiae. Symptoms of proctitis in men with rectal gonorrhoea with or without concurrent chlamydial infection were significantly higher than in men with isolated chlamydial infection (27% versus 10% [chi2=17.55; P<0.0001]). There was, however, no significant difference in the prevalence of symptoms between those with rectal gonorrhoea only (28%) and those with concurrent chlamydiae (23%); chi2=0.11; P>0.05). The median prepatent period or rectal gonorrhoea (21 men) was 5.0 days (interquartile range 11.0 days).