Objective To demonstrate the side effects of malariotherapy and to explore safe procedures in conduct of malariotherapy for human immunodeficiency virus (HIV) infected patients Methods Twenty HIV/ acquired immunodeficiency syndrome (AIDS) patients were selected for the study of malariotherapy and were intravenously infected with Plasmodia vivax to induce therapeutic malaria Malaria was terminated with chloroquine after 10-20 malarial febrile episodes Clinical assessments were made before (baseline), during (malarial phase) and after (post) termination of malaria The density of Plasmodia in peripheral blood from the HIV/AIDS patients were compared to that from HIV negative naturally infected malarial patients who donated the blood for the therapeutically induced malaria CD 4 cell baseline levels were correlated to the severity of malarial symptoms and parasitemia Results There were no significant differences of Plasmodium density between the HIV/AIDS patients injected with P vivax and the HIV negative blood donors However, it was found that the HIV positive patients had milder malarial symptoms and parasitemia with progressively lower CD 4 cell baseline levels All patients developed every day or every other day fever episodes with headache and shaking chill These symptoms were well tolerated with the aid of anti pyretic medications Spleen and liver enlargement were seen in 15 of 20 and 4 of 20 patients respectively Transitory liver effects with increase of serum glutamic pyruvic transaminase were seen in 2 of 20 during malarial phase Most patients experienced mild to medium anemia and 6 of 20 patients developed thrombocytopenia during malarial phase All these side effects disappeared after termination of malaria or within one month thereafter No complications occurred in these patients Conclusions Therapeutically induced acute vivax malaria was well tolerated in 20 HIV positive subjects who represented a range of CD 4 cell levels from 1868/μl to 15/μl Malariotherapy did not induce complications while increasing CD 4 cell levels in most treated HIV/AIDS patients (results published elsewhere) Objective To demonstrate the side effects of malariotherapy and to explore safe procedures in conduct of malariotherapy for human immunodeficiency virus (HIV) infected patients Methods Twenty HIV / acquired immunodeficiency syndrome (AIDS) patients were selected for the study of malariotherapy and were intravenously infected with Plasmodia vivax to induce therapeutic malaria Malaria was terminated with chloroquine after 10-20 malarial febrile episodes Clinical assessments were made before (baseline), during (malarial phase) and after (post) termination of malaria The density of Plasmodia in peripheral blood from the HIV / AIDS patients were compared to that from HIV positive naturally infected malarial patients who donated the blood for the therapeutically induced malaria CD 4 cell baseline levels were correlated to the severity of malarial symptoms and parasitemia Results There were no significant differences of Plasmodium density between the HIV / AIDS patients injected w ith P vivax and the HIV negative blood donors However, it was found that the HIV positive patients had milder malarial symptoms and parasitemia with progressively lower CD 4 cell baseline levels All All patients developed every day or every other day fever episodes with headache and shaking chill These symptoms were well tolerated with the aid of anti pyretic medications Spleen and liver enlargement were seen in 15 of 20 and 4 of 20 patients respectively Transitory liver effects with increase of serum glutamic pyruvic transaminase were seen in 2 of 20 during malarial phase Most of adults experienced mild to medium anemia and 6 of 20 patients developed thrombocytopenia during malaria phase or these months effects disappeared after termination of malaria or within one month total of those patients Conclusions Therapeutically induced acute vivax malaria was well tolerated in 20 HIV positive subjects who represented a range of CD 4 cell levels from 1868 / μl to 15 / μl Malariotherapy did not induce complications while increasing CD 4 cell levels in most treated HIV / AIDS patients (results published elsewhere)