Objectives: To determine what proportion of men who have sex with men (MSM) attending genitourinary medicine (GUM) clinics are offered and accept an HIV test and to examine clinic and patient characteristics associated with offer and uptake. Methods: A cross-sectional study of all GUM clinics in the United Kingdom, involving a case note review of up to 30 patient records per clinic and the completion of a clinic policy form. Results: Overall, 86% of MSM were offered a test and of those 82% accepted a test. Attending with symptoms of a sexually transmitted infection (STI), fewer numbers of partners in the past three months and having tested previously were all independently associated with a decreased likelihood of being offered a test. Attending with symptoms of an STI, increasing age, never having had a risk from unprotected anal intercourse or a previous HIV test and increasing time to wait for results were all independently associated with a decreased likelihood of a patient accepting a test. Only a quarter of clinics reported a written policy for HIV testing intervals among MSM; however, all clinics reported offering testing to all new MSM patients at first screening. The testing policy for reattending patients was less clear. Conclusions: Testing must reach those at most risk and those less likely to test in order to reduce further the proportion of undiagnosed HIV infection. This study suggests that opportunities to detect infection may be being missed and a move towards universal testing of all MSM attending with a new episode, as well as testing within the window period, is recommended.