Objective To explore the mechanisms of malariotherapy for human immunodeficiency virus (HIV)-infected patients and to identify which stage(s) of HIV infection is suitable for the treatment of malariotherapy. Methods Therapeutic acute vivax malaria was induced and terminated after 10 fever episodes in 12 HIV-1-infected subjects: Group 1 (G1) had 5 patients with CD4 T-cell counts500/μl at baseline, Group 2 (G2) had 5 patients with CD4 at 499-200/μl and Group 3 had 2 patients with CD4<200/μl (not included in statistical analysis). Enzyme-Linked-Immuno-Sorbent Assay (ELISA) was used to measure plasma levels of cytokines and soluble activation markers. Flow cytometry was used to measure levels of lymphocyte subsets and phenotypes and CD4 cell apoptosis. Bayer bDNA assay was used to test plasma levels of HIV-1 RNA (viral load). Samples were taken and tested twice before malaria (baselines), three times during malaria and seven times after termination of malaria (at day 10 and 1, 3, 6, 12, 18 and 24 months). Results Levels of plasma tumor necrosis factor-α (TNF-α), soluble TNF-α receptor-2 (sTNF-RII), neopterin (NPT) and soluble IL-2 receptor (sIL-2R) significantly increased during malaria and sharply reduced to baselines post malaria in all groups. Stronger responses of the aforementioned factors were seen in G2 than in G1 during malaria (P=0.081, 0.001, 0.013, 0.020). CD4 count and percentage; CD4/CD8 ratio and CD25 + and CD4 +CD25 + percentages increased but HLA -DR + percentage decreased either during or post malaria in G2. Most G2 patients experienced sustained increase but most G1 patients underwent natural history decline of CD4 counts and percentages during 2-year follow-up. Percentage of apoptotic CD4 cells decreased post malaria in all groups. G3 patients had weaker immune responses, however, one advanced AIDS patient in this group experienced clinical improvement after malariotherapy. Most of the 12 patients experienced increase of HIV viral load during malaria but the viral load returned to baseline levels 1-3 months after cure of malaria and remained near baseline levels for up to two years. Conclusions Part of the mechanisms of malariotherapy is to induce high levels of cytokine activities and subsequently the changes of T-lymphocyte subsets and phenotypes in HIV-infected patients.These findings suggest that malariotherapy may treat HIV-1-infected patients whose CD4 baselines are in the range of 500-200/μl. Objective To explore the mechanisms of malariotherapy for human immunodeficiency virus (HIV) -infected patients and to identify which stage (s) of HIV infection is suitable for the treatment of malariotherapy. Methods Therapeutic acute vivax malaria was induced and terminated after 10 fever episodes in 12 HIV-1-infected subjects: Group 1 (G1) had 5 patients with CD4 T-cell counts500 / μl at baseline, Group 2 (G2) had 5 patients with CD4 at 499-200 / μl and Group 3 had 2 Patients with CD4 <200 / μl (not included in statistical analysis). Enzyme-Linked-Immuno-Sorbent Assay (ELISA) was used to measure plasma levels of cytokines and soluble activation markers. Flow cytometry was used to measure levels of lymphocyte subsets and Phenotypes and CD4 cell apoptosis. Bayer bDNA assay was used to test plasma levels of HIV-1 RNA (viral load). Samples were taken and tested twice before malaria (baselines), three times during malaria and seven times after termination of malaria day 10 and 1, 3, 6 , 12, 18 and 24 months. Results Levels of plasma tumor necrosis factor-α, soluble TNF-α receptor-2 (sTNF-RII), neopterin (NPT) and soluble IL- 2R) increased increased during malaria and sharply reduced to baselines post malaria in all groups. Stronger responses of the above mentioned factors were seen in G2 than in G1 during malaria (P = 0.081, 0.001, 0.013, 0.020). CD4 count and percentage; CD4 / CD8 ratio and CD25 + and CD4 + CD25 + percentages increased but HLA-DR + percentage decreased either during or post malaria in G2. Most G2 patients found sustained increase but most G1 patients underwent natural history decline of CD4 counts and percentages during during 2- year follow-up. Percentage of apoptotic CD4 cells decreased post malaria in all groups. G3 patients had weaker immune responses, however, one advanced AIDS patient in this group experienced clinical improvement after malariotherapy. Most of the 12 patients experienced increase of HIV viral l oad during malaria but the viral load returned to baseline levels 1-3 months after cure of malaria and remained near baseline levels for up to two years. Conclusions Part of the mechanisms of malariotherapy is to induce high levels of cytokine activities and subsequent the changes of T -lymphocyte subsets and phenotypes in HIV-infected patients. These findings suggest that malariotherapy may treat HIV-1-infected patients whose CD4 baselines are in the range of 500-200 / μl.