Previous research has documented the various challenges people living with HIV face as they navigate intimate relationships, including what is often referred to as disclosure. In studies of gay, bisexual and other men who have sex with men, the issue of telling or not telling others about an HIV-positive status has been examined primarily in relation to communication with sexual partners, with few studies focusing on other aspects of intimacy. Drawing on interviews with gay men living with HIV, conducted in four clinics in London, this article explores the narratives of men who have been asked by female friends about the possibility of being a sperm donor. The narratives highlight layers of complexity which have received little attention, not only in research on HIV but also in studies of sperm donation and co-parenting. The article advances dialogue between these two largely separate bodies of work. Our data suggest that reluctance to share an HIV-positive status with others can be an important factor in deciding how to answer the 'sperm donor question'. Examining reproductive relationships of a specific kind - those based on friendships between women and gay men - the article develops the understanding of how secrecy about HIV shapes intimate lives.