Objectives: Since 1999, HIV testing is routinely offered to all attendees of the sexually transmitted infections (STI) outpatient clinic in Amsterdam, the Netherlands. This study evaluates whether this more active HIV-testing policy increased uptake of HIV testing and awareness of an HIV-positive serostatus among heterosexual attendees. Methods: In addition to routine data collected at each STI consultation, data from half-yearly HIV surveys were used from 1994 to 2004. During each survey period, 1000 consecutive attendees are enrolled voluntary and anonymously for HIV testing and are interviewed on previous HIV testing and outcome. Trends in and predictors for uptake of HIV testing as offered during routine STI consultation were analysed by logistic regression. Trends in awareness of an HIV-positive serostatus as obtained from the anonymous HIV surveys were likewise analysed. Results: The percentage of heterosexual attendees opting for an HIV test during consultation increased from 13% in 1996 to 56% in 2004. However, the proportion of individuals aware of their HIV infection did not change over time and only a minority (19%) of the 108 attendees found HIV-positive in the anonymous surveys were aware of their HIV infection. Persons being or visiting a commercial sex worker, having a non-Dutch ethnicity, lacking health insurance and having an STI diagnosed were less likely to opt for an HIV test. Conclusions: Although heterosexual attendees increased their uptake of HIV testing during STI consultation over time, uptake of testing by attendees at risk for HIV infection, such as those infected with an STI, remained low. As a result, the percentage of persons aware of their HIV infection remained low, posing a risk for their individual health and for ongoing HIV transmission. Current testing strategies, therefore, misses the group that most needs testing. Based on these results, ‘opt-out’ HIV testing is now the standard procedure at the Amsterdam STI clinic.