DNA adducts induced by alkenes were studied in in vitro systems (cell cultures) and in experimental animals. Properties of DNA adducts, their relationship with other parameters of genotoxic effect and DNA repair were followed. Based on these results, human biomonitoring studies were conducted in order to elucidate the effect of exposure on enhanced levels of DNA and haemoglobin adducts, single-strand breaks in DNA and HPRT mutant frequencies. Surprisingly, no correlation was found between primary DNA lesions and HPRT mutant frequencies, suggesting that no simple quantitative relationship could be drawn between primary DNA damage and mutagenesis. In order to understand mechanisms of genotoxic effects of xenobiotics, further studies aimed at individual susceptibility, individual repair capacity and the role of specific DNA adducts in mutagenesis, are required.