1. The platelets of 20 uremic subjects were studied, utilizing the following procedures; phase platelet count, serum prothrombin time, thromboplastin generation test with evaluation of plasma, serum, and platelet reagents.
2. Platelet phospholipids from these subjects were used as reagents in the thromboplastin generation test and examined by means of silicic acid paper and column chromatography.
3. Thrombocytopenia was the most common abnormality encountered and was associated with either normal or abnormal prothrombin consumption. Some patients demonstrated defective prothrombin utilization despite normal platelet counts, but their platelets had normal thromboplastic activity, as did those of all patients studied.
4. The paper chromatographic pattern of the phosphatides in all subjects was the same as that reported for normal platelets. Similar results were obtained on column chromatographic analysis of a pooled extract from nine of the uremic patients.
5. On the basis of these studies it was not possible to demonstrate a qualitative platelet defect in uremia.