End-stage chronic renal failure (CRF) is often associated with platelet' disfunction and therefore with impaired hemostasis. Several investigators have reported that rHu Epo, used in the treatment of CRF anaemia, is able to activate a broad spectrum of hematopoietic stem cells, and therefore is able to increase the number of platelets and to induce correction of platelet disfunction. In order to investigate hemostasis changes associated with rHu Epo we studied 8 dialysis patients before and 12 weeks after rHu Epo. RHu Epo did not induce any change in the number of platelets (187710 +/- 52690 vs 204430 +/- 68710; p = NS), but seemed to improve its function (MI% of aggregation with ADP: 46.3 +/- 4.4% vs 49.1 +/- 5.3%; p less than 0.05). There was an improvement in PT (79.0 +/- 3.0% vs 87.5 +/- 8.9%; p less than 0.02) and aPTT (33.3 +/- 5.9" vs 29.3 +/- 2.1"; p less than 0.05) suggesting an improvement in platelet coagulant activities. These preliminary results indicate that rHu Epo does not increase the number of platelets but can induce a correction of platelet disfunction.