Cross sectional and longitudinal data on condom use among homosexually active men is presented. Data pertain to two waves of interviewing (1987/8 and 1991) from Project SIGMA, a large longitudinal study of male homosexual behaviour in the light of HIV. Aggregate changes across the time-period indicate an increase in condom use for both insertive and receptive anal intercourse, particularly high with casual partners. Condom use is still much more prevalent with casual rather than regular partners. Longitudinal analysis show considerable changes at the individual level, with almost a third of men changing their practices. Half of those decreased their risk behaviours, whilst the other half increased them. Less than 1% used condoms for fellatio in the year preceding the 1991 interview, but 8.3% had used other barriers during sex, primarily for hygiene and fun reasons, rather than as disease prophylaxis. Some implications are drawn for condom promotion and HIV prevention. AJ Hunt, P Weatherburn, FCI Hickson, PM Davies, TJ McManus, APM Coxon