The stimulation of platelets production by human hemopoietic growth factors, became an interesting alternative in the treatment of thrombocytopenic patients. Because the lineage specific Colony Stimulating Factor of Megakaryocytes (CSF-Meg) has not yet been discovered, the aim of our study was to compare the stimulatory potential of different hemopoietic growth factors influencing megakaryocytic colony formation in vitro. According to our results the best strategy to stimulate human megakaryocytopoiesis in vivo seems to be simultaneous or sequential use of the mixture of several cytokines including: interleukin-3, interleukin-6, erythropoietin or kit ligand. The best stimulatory effect we have obtained however, using recently developed by molecular biology means recombinant fusion protein composed of joined by peptide bridge interleukin-3 and erythropoietin molecules. The data presented in this paper, could find application in the near future by elaborating more effective clinical protocols for treatment of thrombocytopenia using hemopoietic growth factors.