Despite prevention efforts, the incidence of sexually transmitted infection among HIV-positive men who have sex with men remains high, which is indicative of unchanged sexual risk behaviour. Discussing sexual risk behaviour has been shown to help prevent sexually transmitted infections among HIV-positive men who have sex with men.The aim of this study was to identify factors that influence whether - and how - specialised HIV nurses discuss sexual risk behaviour with HIV-positive men who have sex with men. Identifying these factors could indicate how best to improve the frequency and quality of discussions about sexual risk behaviour, thereby reducing sexual risk behaviour and sexually transmitted infections.Qualitative study, focus groups among HIV nurses.Dutch HIV treatment centres.A purposive sample was taken of 25 out of 87 HIV nurses working in one of the 26 specialised HIV treatment centres in the Netherlands. Of the 25 HIV nurses we approached, 22 participate in our study.Three semi-structured focus group interviews were held with 22 HIV nurses from 17 hospitals. Interviews were transcribed verbatim, and thematic analysis was performed.HIV nurses agreed that discussing sexual risk behaviour is important, but barriers were experienced in relation to doing so. In accordance with the theory of planned behaviour, attitudes, perceived norms and perceived behavioural control were all found to be relevant variables. Barriers to discussing sexual risk behaviour were identified as: dealing with embarrassment, the changing professional role of an HIV nurse, time constraints, and the structure of the consultation.To improve the frequency and quality of discussions about sexual risk behaviour with HIV-positive men who have sex with men, our data suggests it would be beneficial to support HIV nurses by developing tools and guidelines addressing what to discuss and how. Using a related topic as a conversational 'bridge' may help nurses to broach this subject with their patients. This would allow HIV nurses to discuss possible risk reduction strategies, such as pre-exposure prophylaxis for HIV-negative partners, condom use, strategic positioning, or sero-sorting.