Leptin is a protein hormone produced predominantly by adipocytes. Its serum concentrations under stabilised energy balance reflect the total body fat content. Serum leptin levels represent an important peripherial signal informing the hypothalamic satiety center about the body fat stores. Apart from the above mentioned functions the possible physiological significance of leptin in the regulation of angiogenesis, blood pressure, sexual maturation etc. is suggested. The long isoform of leptin receptor belongs to the cytokine receptors group. The leptin receptors were identified in some haematopoietic stem cells. Leptin was found to stimulate the proliferation of haematopoietic stem cells either alone or in combination with some cytokines. Leptin thus seams to represent an additional factor that plays a role in the haematopoiesis regulation as it was demonstrated by some experimental studies. However, this suggestion needs to be further confirmed by clinical studies exploring the changes of serum leptin levels in various phases of haemotological diseases and during their treatment.

        Key words: leptin, haematopoiesis, leptin receptor, cytokines.