Objective: Sclareol (sclacol) is one organic compound extracted from sage clary plants. Recent study has shown its anti-tumor effects against breast cancer, gastric carcinoma, osteosarcoma and colorectal cancer. Its detailed mechanisms in inhibiting tumor growth, however, remained unknown. This study thus observed the effect of sclareol on the proliferation of osteosarcoma cells, in an attempt to investigate the role of sclarcol on osteosarcoma growth. Patients and methods: MG63 osteosarcoma cell was treated by different concentration of sclarcol. CCK8 assay was used to test its effect on cell proliferation. LC50 value was then determined to obtain optimal treatment dosage. MG63 cells were then divided into control and drug treated group, and were tested for apoptosis using flow cytometry. Rhodamine 123 was used to label mitochondrial membrane potential, which was measured by laser confocal microscope. Results: CCK8 test results showed that sclareol can inhibit MG63 cell proliferation, with an LC50 value at 11.0 μM. Flow cytometry results showed the apoptotic cell ratio at 13.8%, 24.1% and 37.3% after applying 2.0 μM, 4.0 μM and 8.0 μM sclareol. Compared to control group, sclareol significantly depressed mitochondrial membrane potential of MG63 cells. Conclusion: Sclareol can inhibit the proliferation of MG63 cells, and induce cell apoptosis and decrease mitochondrial membrane potential. These results suggested the inhibition of osteosarcoma cells by sclareol via both apoptosis induction and decreasing mitochondrial membrane potential.