Four new diene valepotriates, sorbifolivaltrates A-D ( 1- 4), and the known compounds isovaltrate ( 5), valtrate ( 6), seneciovaltrate ( 7), valtrate hydrine B3 ( 8), and valtrate hydrine B7 ( 9), have been isolated by bioassay-guided fractionation of the cytotoxic hexanes and methyl ethyl ketone crude extracts of the aerial parts of Valeriana sorbifolia occurring in the Sonoran desert. The structures of 1- 4 were determined on the basis of their high-resolution mass spectrometric and NMR spectroscopic data. All compounds exhibited weak to moderate cytotoxicity against the human metastatic prostate cancer cell line, PC-3M.