The hazardous biochemical effects of the malarial parasite Plasmodium vivax and Plasmodium falciparum was comparedin the blood of Afghan patients. The role of glucose-6-phosphate dehydrogenase (G-6-PD) and immunoglobulins (lgs) was also detected in the increased incidence of malaria in Afghans. Blood biochemical analysis for bilirubin, serum glutamate pyruvate transaminase (SGPT), G-6-PD and lgs was conducted in hundred Afghan malaria patients coming in Malaria Control Centre, Quetta. Patients were grouped according to the form of species present. An increase of 1.0 - 2.0 mgs% of Bilirubin was observed in 14% patients, while rise in SGPT was associated to 50% patients. None of the patients were found to be deficient in G-6-PD activity. The most significant finding was a low rise of lgs, limited to less than 50% patients only. Thus, P. falciparum appears to produce more hazardous effects.