High rates of both illicit drug use and depression are consistently reported among gay men. However, little is known about how beliefs about drug use shape clinical encounters between gay men and health professionals, and that in turn affect clinical communication and care, particularly in relation to depression. We compared ‘doctor’ and ‘patient’ beliefs about the role of illicit drug use in gay men’s depression. Semi-structured interviews were conducted during August–December 2006 with 16 general medical practitioners working in seven ‘gay-friendly’ practices in Sydney, Adelaide and a rural-coastal city in New South Wales, and during February–May 2008 with 40 gay men with depression recruited through four Sydney and Adelaide practices. A thematic analysis of these two sets of interviews found that doctors expressed the beliefs that: illicit drug use is related to depression in gay men; illicit drug use impedes effective diagnosis and treatment of depression in gay men; and illicit drug use increases the level of complexity involved in caring for gay men with depression. Gay men expressed the beliefs that: illicit drug use is closely related to depression; illicit drug use can be helpful in dealing with difficult experiences; and illicit drug use is just what you do as a gay man living in a big city. Both groups believed drug use and depression were related, but doctors emphasised the negative outcomes of drug use and interpreted these in relation to health. Gay men believed that drugs could have both negative and positive uses and differentiated between health and social outcomes. While the doctors articulated a pragmatic position on drug use, which is consistent with harm reduction principles, communication with gay male patients could be enhanced if both groups acknowledged their divergent views of illicit drugs and their potential role in mental health.