Effects of potassium sulphate (K2SO4) on mitosis, cell cycle and chromosomes in Vicia faba L. seeds germinated at extreme temperatures were studied as flowcytometrically and cytogenetically. Seeds germinated at high (30 degrees C) and low temperatures (4 degrees C) showed a significant decrease in mitotic index as compared to those of optimum temperature conditions. 50 and 250 mu M K2SO4 were successful in alleviating the negative effects of high and low temperature on mitotic activity and cell cycle respectively. These concentrations increased the cell division removing or decreasing the negative effects of temperature stress. Chromosomal aberrations were not observed in cells of seeds germinated in distilled water and also at any temperatures. However, the frequency of aberrations increased significantly by increasing K2SO4 concentration. The highest aberration frequency in all temperature degree tested was found at 1000 mu M K2SO4 concentration.