This paper presents the results of a study on the influence of lead, copper, manganese and cadmium on DNA integrity in plant cells. Plants, as biological indicators, can measure the potential effects of pollutants when they are used to measure effects of heavy metals. The genotoxicity of heavy metals in kidney-bean (Phaseolus vulgaris) seedlings was subjected to RAPD (random amplified polymorphic DNA) analysis. An RAPD 'fingerprinting' technique was used to detect DNA damage in the kidney-bean seedlings treated with two selected heavy metals at concentrations of 150 and 350 mg x l(-1). Polymorphisms became evident as the presence and/or absence of DNA fragments in treated samples compared with the untreated one. At 350 mg x l(-1), a high number of both missing bands and new amplified fragment were observed. Results suggested that a qualitative measure reflecting changes in RAPD profiles were significantly affected at higher concentrations (350 mg x l(-1)) of the tested heavy metals. A total of 467 RAPD fragments in RAPD profiles were detected by using six random primers (decamers) and 224 of these fragments showed polymorphism. There was a distinct distance between the band patterns of treated plants and the control samples when the cluster method was applied. In addition, the result derived from numerical analysis revealed a considerable distance between the band pattern of the plant samples treated with 350 mg x l(-1) heavy metals and the control sample. Finally, a comparison between untreated and treated genomes shows that RAPD analysis can be used to evaluate how the environmental pollutants modify the structure of DNA in living organisms.