Objectives: The aim of the study was to investigate whether high endogenous levels of insulin-like growth factor-1 (IGF-1) and its binding protein-3 (IGFBP-3) were related to a faster reconstitution of different blood cell populations in the early phase after allogeneic myeloablative haematopoietic stem cell transplantation (HSCT). Methods: We measured IGF-1 and IGFBP-3 by chemiluminescence during the first three weeks after transplantation in 35 adult patients undergoing myeloablative HSCT and calculated area under the curve divided by time (AUC/t) for each patient. Results: Circulating levels of IGF-1 and IGFBP-3 correlated with counts of reticulocytes (r_s= 0.44, p =.011 and r = 0.41, p =.017, respectively) and thrombocytes (r_s = 0.38, p =.030 and r_s = 0.56, p =.0008) three weeks post-transplant. Furthermore, high IGFBP-3 levels correlated with absolute lymphocyte counts 3 weeks post-HSCT (r_s = 0.54, p =.012) and were associated with shorter time to neutrophil engraftment (r_s = −0.35, p =.043). Both IGF-1 and IGFBP-3 levels were associated with the number of circulating natural killer cells one month after HSCT (r_s = 0.42, p =.032 and r_s = 0.57, p =.0026). Conclusion: These data indicate that high levels of IGF-1 and IGFBP-3 relate to a faster haematopoietic reconstitution after HSCT and suggest a biological influence of these mediators in haematopoietic homeostasis in these patients.