The relationship between grade of pulmonary hypertension and factors associated with human immunodeficiency virus among patients with HIV infection is poorly documented. This report documents the most extensive attempt made thus far to determine whether a relationship exists between degree of pulmonary hypertension and the following conditions: HIV risk factor, degree of immunosuppression, presence or absence of AIDS, and presence or absence of liver cirrhosis. A retrospective study involving a search of the published literature on primary pulmonary hypertension among HIV cases from 1987 to 1998, using the Medline and Aidsline databases was conducted. Patients for whom secondary causes of pulmonary hypertension could be excluded were selected, and the following information for each was recorded: age, gender, risk factors for HIV infection, HIV disease stage according to the Centers for Disease Control, previous opportunistic and neoplastic diseases, CD4+ cell count (cells/L), presence or absence of liver cirrhosis, pulmonary systolic artery pressure level, and lung pathology specimens. Information about the patient's survival time was also recorded. Seventy-six patients were judged to have primary pulmonary hypertension and were included in the study. While no correlation was found between pulmonary systolic artery pressure level and CD4+ cell counts, a statistically significant difference was found between HIV-positive patients with and without AIDS as determined by the Centers for Disease Control criteria with regard to the degree of pulmonary hypertension, expressed as pulmonary systolic artery pressure level (85.4 +/- 17 mm Hg vs 71.8 +/- 15 mm Hg, p < 0.013). Although a higher PAPS was present in HIV cirrhotic patients, a statistically significant difference was not found between degree of pulmonary hypertension and evidence of hepatic cirrhosis (85 +/- 21 mm Hg vs 73.1 +/- 15 mm Hg, p < 0.062). Patients with AIDS and primary pulmonary hypertension present a higher degree of pulmonary hypertension than non-AIDS patients. Pulmonary hypertension associated with HIV seems to be related to a cytokine-related stimulation and proliferation of endothelium. High levels of cytokines present in AIDS patients can favor pulmonary hypertension, but the role of a host response to HIV--determined by one or more HLA subtypes--is suspected to enhance high cytokine production levels.