Three cases of immune thrombocytopenia (ITP) associated with human immunodeficiency virus (HIV) infection prompted a review of community‐acquired thrombocytopenia in Nova Scotia from January 1980 to December 1987. Two hundred and seven patients meeting the case definition of ITP were identified. The incidence of ITP rose from 2.0×105 in 1980 to 3.3×105 in 1987. More cases of ITP in the sexually active population occurred between 1984 and 1987 than in the previous four years (P=0.034). All three cases of known HIV associated ITP were captured in the retrospective surveillance system. The study concluded that increases in community‐acquired ITP in a sexually active population may be a surrogate marker of the HIV epidemic, even in geographic areas with a low seroprevalence for HIV. Serological tests for HIV infection should be a routine part of the diagnostic investigation of ITP in all sexually active patients or those with other potential risk factors for HIV infection.