Background: thrombocytopenia may be defined as a decrease in number of platelets in the circulating blood. Bone marrow examination may be required to discriminate causes of thrombocytopenia as hypoproductive or hyperdestructive. However, this procedure is invasive and time consuming. Objective: this study aims to assess the diagnostic value of mean platelet volume (MPV), platelet distribution width (PDW) and platelet large cell-ratio (P-LCR) and anti-platelet antibody in discriminating causes of thrombocytopenia as hypoproductive or hyperdestructive immune thrombocytopenia purpura (ITP). Patients and Methods: the study was conducted on 45 subjects15 patients suffering from ITP, 15 patients suffering from other causes of thrombocytopenia, and 15 healthy controls. All of them were subjected to full clinical history, examination and routine investigation including CBC, routine chemical analysis (liver function, renal function, etc.), BM aspirate and detection of antiplatelet antibody. Results: the results of this study revealed that in ITP patient group, we found that the MPV, PDW and P-LCR were significantly higher in comparison to non-ITP group. As regard anti-platelet antibody detection by ELISA method was positive (60%) in ITP group, positive (26.7) in nonITP group and negative in all patients in control group. It revealed no significant difference between ITP group and non-ITP group to diagnose ITP. Conclusion: from this study, we could conclude that, measuring of platelet indices (MPV, PDW and LCR) provides useful diagnostic test in differentiating ITP from hypoproductive thrombocytopenia, thus may avoid the need for bone marrow examination. Measurement of anti-platelet antibody is not a reliable test in diagnosis of ITP.