A case of type IV Ehlers-Danlos syndrome with a partial platelet delta-storage pool disease is reported. The diagnosis of Ehlers-Danlos was clinical. The platelet-dense granule deficiency was determined by ultrastructural platelet morphology. Dense bodies were decreased in number, and most showed loss or fragmentation of electron-dense material. Aggregation studies revealed a retarded response to ristocetin and arachidonic acid, which was corrected with desmopressin acetate-DDAVP.