Most patients with HIV infections are asymptomatic or minimally symptomatic. Primary care physicians can play a unique and vital role in their care. They should: 1. Look for cases. Treatment can prevent or delay progression of disease. 2. Know how to interpret the serologic tests for HIV infection. 3. Collect an adequate data base to assess extent and severity of disease and screen for certain coexisting infections. 4. Intervene appropriately with counseling and prophylactic therapy. 5. Refer early when neoplasia, opportunistic infections, or diagnostic uncertainties occur.