The platelet membrane glycoproteins (GP) of myeloproliperetion disorders(12 cases) were analyzed by SDS PAGE. In GP I peak there was no difference between normal and this disorders in the 125I incorporation rate but the percentage of GP I to all PAS stained peaks was reduced in chronic myelogenous leukemia (CML) but increased in primary thrombo-cythemia(PT) polycythemia vera(PV) and myelofibrosis (MMM). In GP m peak of CML, the increased percent of PAS staining and the decreased 125I incorporation rate were proved compared to the control. In other myeloproliferative disorders, it was shown that the percent of PAS staining was normal but 125I incorporation rate was decreased against GP III. To analyse the dissociation between PAS stain and 125I incorporation rate, the two dimensional electrophoresis was conduced with non reduced-reduced system. The autradiographic pattern of this electrophoresis disclosed seven 125I incorporated spots (GP Ia, Ib, Ic, IIa, IIb, III and IV) in normal platelets. GP Ib was exposed as an unclear spot in CML (4/6). GP IV appeared as a most dense spot in control but were divided in two spotsimain large and small satellite fragment in 4 of 6 CML and in one of PV and MMM. This findingsuggested a heterogeneity of membrane glycoprotein in these disorders.