Some alterations in blood parameters that would aid the diagnosis of malaria caused by Plasmodium falciparum were investigated. These alterations include; oligocythaemia, leucopenia, thrombocytopaenia, anaemia, decreased packed cell volume and elevated erythrocyle sedimentation rates. These are all largely attributed to the invasion of haematopoietic organs like the spleen and bone marrow by the malaria parasites which slowed down haematopoietic rates. Consequently, the rate of erythropoiesis, leucopoiesis and thrombocytosis were reduced. The pathogenesis of anaemia with its concomitant oligocythaemia and reduced haematocrit during malaria is due to the parasites’ primary target which are the erythrocytes and bone marrow dysfunction. Leucopenia could be attributed to localization of leucocytes away from peripheral circulation, splenic sequestration and other marginal pools, and not actual depletion or stasis. Thrombocytopaenia could be due to excessive removal of thrombocytes by splenic pooling or due to platelet consumption by the process of disseminated intravascular coagulopathy. It could be due to shortened life span of the blood platelets as a result of elevated blood anti blood platelet antibodies (1gG) which bind to platelet bound malaria antigens leading to increased destruction of circulating blood platelets. When some of these haematological changes are combined with other clinical and microscopy methods, malaria diagnosis could be improved.