Two new lathyrane-type diterpenoids, jatropodagins A and B (1 and 2), and five known analogues (3−7), were isolated from the stems of Jatropha podagrica. Their structures and absolute configurations were elucidated by spectroscopic data and calculated ECD analyses. The cytotoxicities of all the lathyrane-type diterpenoids (1−7) were evaluated against two human osteosarcoma cell lines (Saos-2 and MG-63).Compound 1 exhibited significant cytotoxic effects against Saos-2 and MG-63 with IC 50 values of 8.08 and 14.64 μM, respectively. The IC 50 values for the positive control 5-FU against the Saos-2 and MG-63 cell lines were 19.01 and 25.00 μM, respectively. Morphological features of apoptosis activities were evaluated in 1-treated Saos-2 cells and the results confirmed apoptosis in a dose-dependent manner.