Introduction: Thrombocytopenia is the most common cause of abnormal bleeding and can result from Hyper destruction of platelets, Hypoproduction of platelets and Abnormal platelet pooling. The aim of this study was to evaluate role of platelet indices (MPV, PDW, PCT) in diagnosing various causes of thrombocytopenia. In this observational analytic study 600 st Methodology: udy samples were divided into two groups: 300 cases diagnosed as thrombocytopenia (1.5 lakhs /microliter) and 300 healthy control. Cases of thrombocytopenia were further classied in 3 categories depending upon the predominant mechanism of thrombocytopenia. Statistical Analysis: Mean and SD of platelet count, mean platelet volume (MPV), platelet distribution width (PDW) and plateletcrit (PCT) in each group was calculated and compared among groups using unpaired T- test. Out of 300 cases of Thrombocytopenia, Group A constituted 224 cas Results: es (75%) due to hyper destruction of platelets, Group B constituted 72 cases (24%) due to hypoproduction of platelets and Group C constituted 4 cases (1%) of Thrombocytopenia due to abnormal pooling of platelets. On comparing mean MPV and PDW values among groups, the MPV and PDW of hyper destructive thrombocytopenia was found to be higher than mean MPV and PDW of hypo productive thrombocytopenia as well as control group. The mean PCT of hyper destructive group was higher than that of hypo productive group. Combined interpretati Conclusion: on of platelet count and platelet indices are of signicant discriminating value in differentiating various causes of thrombocytopenia thus their standardized measures can signicantly increase its utility in diagnosis and understanding mechanism of various clinical condition