BACKGROUND: The preventive effects of antiretroviral treatment (ART) on onward transmission of HIV are a major reason for broadening eligibility for ART. In the WHO European Region, surveillance reveals substantial differences in access to ART across regions and sub-populations. We analysed self-reported data on ART and reasons for not taking ART from EMIS, a large Pan-European Internet survey among men-who-have-sex-with-men (MSM). METHODS: Respondents from 38 European countries reported their last HIV test result and, if diagnosed with HIV, their treatment status, and reasons for not taking or having stopped ART from a 7 item multiple choice list and/ or answered an open-ended question to give other reasons. Responses were classified as fear of consequences, perceived lack of need, and ART inaccessibility based on factor analysis. Associations between not taking ART because of fear of consequences, and demographic, behavioural and contextual indicators were identified in a multivariable regression model. RESULTS: 13,353 (7.7%) of 174,209 respondents had been diagnosed with HIV. Among them 3,391 (25.4%) had never received ART, and 278 (2.1%) had stopped taking ART. Perceived lack of need was by far the most common reason for not taking or stopping ART (mentioned by 3259 (88.8%) respondents), followed by fear of consequences (428 (11.7%)), and ART inaccessibility (86 (2.3%)). For all reasons, an East-West gradient could be seen, with larger proportions of men living in Central and Eastern Europe reporting reasons other than medical advice for not taking ART. A minority of men were reluctant to start ART independent of medical advice and this was associated with experiences of discrimination in health care systems. CONCLUSIONS: ART is widely available for MSM diagnosed with HIV across Europe. Not being on treatment is predominantly due to treatment not being recommended by their physician and/or not perceived to be needed by the respondent.