The present study was conducted in the Department of medicine,Gandhi Hospital, Secunderabad. 100 malarial fever cases were taken up for the study, which consisted of 79(79%) males and 21% females. Among this, 55% cases were of p.vivax and 45% p.falciparum. The maximum number of cases fell in the age group of 15-35 years (62%). 100% cases presented with fever, chills and rigors. Other presenting symptoms were headache (25%)and vomiting (33%). Splenomegaly was seen in 32% cases, while hepatomegaly in 22%, 15% showed pallor and 8%cases had icterus. Complete hematological tests were done on cases taken for study and analyzed. Anemia ranged from 6.0 to 15.6gm/dl, leukocyte count varied from 1.8 to 17.7cu/mm. Platelet count was done on every patient on day 1, 2, and 3.Thrombocytopenia was seen in 31% (31) cases of p.vivax, 24% of p.falciparum patients. Association of thrombocytopenia and effect of treatment was completely analyzed in both p.falciparum and p.vivax the effect of antimalarial drugs on platelet count was observed. On Day 1 platelet count varied from 15,000 to 1,94,000. On Day 2 platelet count varied from 14,000 to 1,84,000. On Day 3 platelet count varied from 26,000 to 1,98,000.