(+)-Diasesamin (1), (+)-sesamin (2), (+)-episesamin, stearic acid, palmitic acid, a mixture of β-sitosterol and stigmasterol, and a mixture of β-sitosterol-D-glucoside and stigmasterol-D-glucoside were isolated from the stems of Cinnamomum camphora (L.) Presl.. Among these compounds, 1 is obtained for the first time from a natural source. The cytotoxicity of 2 on Hep G2 and HeLa cell cancer lines was also investigated. The flow cytometric assay results indicated that 2 elicited a decrease in the percentage of the S phase of the cell cycle in Hep G2 cells after incubation for 24 h. These results reflect that 2 inhibited the DNA synthetic event in Hep G2 cells.