Objectives To explore the reasons why men who have sex with men (MSM) with diagnosed HIV test for sexually transmitted infections (STIs) away from their usual care provider without disclosing their HIV infection.

Methods Cross-sectional internet panel survey of MSM.

Results 9.4% of men with diagnosed HIV reported ever testing for STIs away from their usual HIV care provider without disclosing their HIV infection, and 4.4% had done so in the last year. Reported benefits were the convenience of using an alternative service and the avoidance of disclosing risky sexual behaviour to known HIV care providers. The impact on continuity of care was seen as a disadvantage of seeking STI screening away from usual care providers. A minority of men who attended an alternative service reported having an HIV test.

Conclusions Prevalence estimates of undiagnosed HIV among MSM may be inflated because some men with diagnosed HIV seek STI testing away from their usual care provider without disclosing their HIV infection or accepting an HIV test. Our data suggest that the reasons for doing so are convenience and discomfort about disclosing risky sexual behaviour to HIV care providers.