The presence of cellular growth factors in peritoneal effluents from CAPD patients have been described. The purpose of this paper has been to evaluate the effects of mitogenic activity of peritoneal effluents of the in vivo and in vitro additions of Calcitriol, EPO and IFN. These drugs were added to nocturnal peritoneal dialysate (in vivo) and to nocturnal effluent (in vitro) and then these fluids were tested for mitogenic-induced capacity on mice and human fibroblasts in culture. Our data show that the addition of Calcitriol and Erythropoietin have little effects on peritoneal effluent behaviour. Interferon alpha-2b seem to be useful for decreasing human fibroblasts growth.