The volatile fractions from Astragalus corniculatus Bieb., cultivated and collected wild, were analyzed at three different phenological phases for the first time. GC/MS analysis showed that the volatile fractions contain hydrocarbons, butyl ethers, acids, alcohols, esters, aldehydes, ketones, terpenes. These fractions were tested for cytotoxic activity in a panel of human tumor cell lines after 48 h, using the MTT-dye reduction assay. Throughout the cytotoxicity evaluation the fraction derived from the flowering phase of wild type plant was found to exert the most prominent cytotoxic activity, which could be ascribed to the high content of hydrocarbons and squalene in particular. Furthermore, the mechanistic elucidation of the mode of action of this volatile fraction in SKW-3 cells revealed that the observed activity is mediated by induction of necrotic type cell death as evidenced by the smear patterns of DNA following a 24 h exposure period.