In the present research protein analysis on SDS-polyacrylamide gel electrophoresis (PAGE) has been used to study the glycoprotein pattern of the blood platelets of four members from a family affected by May-Hegglin anomaly. In order to characterize the glycoprotein fractions, lactoperoxidase-iodination and immunoprecipitation procedures were used. N,N'diallyltartardiamide (DATD) cross-linked gel electrophoresis was shown to improve the glycoprotein pattern resolution, although with the lactoperoxidase-iodination the glycoprotein characterization of May-Hegglin platelets overlapped the normal. On the other hand with the immunoprecipitation the specific antiserum precipitated all the five major fractions of normal membrane glycoproteins, but it was shown to react quite poorly with the component V of the May-Hegglin glycoprotein pattern.