Background: Annexin V is a cellular protein used to detect apoptotic cells by its ability to bind to phosphatidylserine, a marker of apoptosis when it is on the outer leaflet of the plasma membrane.CXCR4 is expressed on cells of megakaryocytic series, especially platelets,  and plays an important role in megakaryopoiesis. Both were used to study the pathogenesis of ITP in children. This study aimed to evaluate Annexin V as a marker of early apoptosis and the CXCR4 expression as a marker of megakaryopoiesis in adult patients with ITP. Patients and methods: This study was conducted on 60 patients with ITP with a mean age of 39.23± 12.49 and 40 healthy subjects with a mean age 36.08± 9.4 as a control group. Using flow cytometry, we investigated apoptotic markers of platelets annexin V and megakaryopoiesis marker CXCR4  expression. Results: The percentage of the platelet with early apoptosis-positive markers (Annexin -D1) were less frequent in the ITP group compared to the control group (p < 0.001), the percentage of the platelet with late apoptosis-positive markers (Annexin -D2), living platelet (Annexin-D3), necrotic platelet (Annexin-D4) were more frequent in the ITP group compared to the control group (p=0.62, p < 0.001, p=0.016) respectively.  The percentage of the platelets with CXCR4 expression was lower in ITP patients compared to the controls (p < 0.001). Conclusion: pathogenesis of ITP in adults is complicated. Platelet Annexin V together with CXCR4 expression may detect apoptosis resistance in adult patients with ITP.