Trichomonas vaginalis (TV) has, in the past, been regarded as a useful marker for other asymptomatic sexually transmitted infections such as gonorrhoea and chlamydia in women. The aim of this study was to determine whether TV is still such a marker. All women attending the Department of Genito-urinary Medicine at the Leeds General Infirmary with a diagnosis of TV during 1983 and 1993 were identified and concurrent infections were tabulated. In 1993 approximately 30% of women with TV had at least one other sexually transmitted infection. The prevalence of gonorrhoea in women with trichomoniasis fell from 20% in 1983 to 10% in 1993 whilst the prevalence of chlamydia in these women remained unchanged at 15%. Thus trichomoniasis is still frequently associated with other pathogens in women and screening of these women for other infections remains essential.