Apart from playing an important role in the primary haemostasis platelets also have different roles in inflammation, atherosclerosis, angiogenesis and antimicrobial host defence. Variation in their size indicates change in their function. Platelet parameters are thought to vary in inflammatory conditions and infections. This study was conducted with the aim to investigate the relationship between PLT count and its parameters, including MPV, PDW and PCT in patients having leucocytosis and leukopenia. Total 462 subjects were studied with 231 cases and controls each. Cases were further subdivided into 51 cases having leukopenia and 180 cases having leucokytosis. The platelet parameters were studied in both leucocytosis and leukopenia cases and compared with controls. P value was calculated.The platelet count, plateletcrit are decreased and MPV is increased in Leukopenia patients. However in patients of leucocytosis, MPV may not provide additional information as MPV is variable parameter and should be interpreted along with other inflammatory parameters.