CD36 is a glycoprotein that is expressed on platelets, monocytes, and endothelial cells. To analyze the mechanism of CD36 deficiency on the platelet membrane, we have examined the expression of mRNA by RT-PCR and the Sau96I site on PCR products. In cases 3, 5, and 6, we have detected the normal size, but few products by agarose gel electrophoresis and in all cases, several restriction enzyme patterns with Sau96I digestion have been observed. These findings suggest that transcriptional control may affect the expression of the CD36 molecule on the platelet membrane and a different mechanism may be present for the transcription of the CD36 mRNA in megakaryocytes from monocytes.