To identify associations between HIV-related experience and patterns of service provision, physicians across Canada were solicited by mail to register in a national network of HIV/AIDS care givers. Respondents provided data about: personal, demographic and practice characteristics; the number of HIV-positive patients ever seen; the nature of the HIV-positive client population; and services provided to HIV-positive patients. Univariate techniques provided a demographic and professional profile of participating physicians. Logistic regression was used to identify associations between level of HIV-related experience and the provision of patient services. The 566 registered physicians have provided care to 56,378 HIV-infected persons and represent every province and territory in Canada. Multivariate analysis revealed that highly experienced physicians were more likely to provide all 3 types of services considered, to practise in Montreal, Vancouver or Toronto, and to be medical specialists (all P < 0.001).