Twenty-one derivatives of taxchinin A (1) and brevifoliol (2) were synthesized and evaluated for cytotoxicity against human non-small lung cancer (A549) cell line. Nine derivatives showed potent activity with IC(50) values from 0.48 to 6.22microM. 5-Oxo-13-TBDMS-taxchinin A (11) and 5-oxo-13,15-epoxy-13-epi-taxchinin A (15) are the most potent derivatives, with IC(50) at 0.48 and 0.75microM, respectively. The structure-activity relationship (SAR) of these compounds established that exocyclic unsaturated ketone at ring C is the key structural element for the activity, while the alpha,beta-unsaturated ketone positioned at ring A has no effect for the activity. The significant cytotoxicity of derivatives 11 and 15 may be due to the conformational change in the taxane rings. The 3D-QSAR study was conducted on this series of compounds, which provided optimal predictive comparative molecular field (CoMFA) model with cross-validated r(2) (q(2)) value of 0.64.