Aim: Sea cucumber has been paid attention in treatment of bone defects due to possessing bioactive compound such as chondroitin sulfate. There were done successful researches in the field of application of mesenchymal stem cells for treatment of bone injury recently. Therefore, this study performed to define the osteogenic and adipogenic potency of Persian Gulf sea cucumber alcoholic extract on differentiation rat bone marrow derived stem cells into osteogenic and adipogenic.Material and Methods: In this experimental study, bone marrow stromal cells were isolated by flushing from male Wistar rat and demonstrated stemness by immunocytochemistry. The cells in 9 experimental group were exposed to various concentration (3.5, 6.25, 12.5, 25, 50, 100, 200, 400, 800 mg/ml) of sea cucumber alcoholic extract and cytotoxicity of sea cucumber alcoholic extract determined by MTT assay. Eventually, after 21 day, osteogenic and adipogenic differentiation were evaluated with alizarin red, oil red staining and alkalin phosphatase kit Data were analyzed by SPSS software, ANOVA and the level of p £ 0.05 was considered significant.Result: An appropriate dosage for treatment of mesenchymal stem cells was determined less than 50 mg/ml. Also, oil red staining showed that sea cucumber alcoholic extract does not have capacity of adipogenic induction while alizarin red staining and alkaline phosphatase revealed that concentration of 25 mg/ml sea cucumber alcoholic extract was most efficient concentration into osteogenic differentiation.Conclusion: Sea cucumber extract was able to differentiate rat bone marrow mesenchymal stem cells into osteogenic lineage.