Objective To explore the effect of insulinlike growth factor1 (IGF-1) on the growth of musclederived stem cells (MDSCs). Methods MDSCs were isolated from the hindlimb muscle of new born mice through serial preplates. DMEM with 2% fetal bovine serum was used to induce MDSCs to differentiate into skeletal muscle lineage. The expression of stem cell marker Sca-1 or skeletal muscle cell marker α-sarcomeric actin was examined by immunocytochemistry SP method. MTT colorimetric microassay was conducted to determine the effect of IGF-1 on MDSCs proliferation. The relationship between functioning and culture time and the relationship between functioning and IGF-1 concentration were studied. Results MDSCs were successfully isolated from the hindlimb of neonatal mice. Over 90% of the MDSCs showed Sca-1 positive immunoreactivity. MDSCs could give rise to α-sarcomeric actin positive myotubes in differentiation cultures. The proliferative effect of IGF-1 on MDSCs increased gradu ally with prolonged culture time. The elevation of IGF-1 concentration also increased the proliferative effect until it came to a saturation point.Conclusion