Effects of salt stress on root growth, mitotic index, nuclear volume, vacuolization, nucleolar distortion and starch content were investigated in Turkish bread wheat (Triticum aestivum L. cvs. Yildiz - salt sensitive, Dagdas - salt tolerant) and durum wheat (Triticum durum L. cvs. C1252 - salt sensitive, Meramsalt tolerant) genotypes which were treated with 150 mM NaCI over a 6-day period. Salt treatment of wheat seedlings resulted in a decrease in root elongation and cell division in all genotypes at the 48 hours. According to controls, wheat root length decrease was 49% for Dagdas, 53.34% for Yildiz, 25.34% for Meram, 53.68% for C1252 at the 48 h. Mitotic index showed a more significant decrease in sensitive genotypes (1.24% for Yildiz, 0.66% for C1252 compairing to their controls 3.85% and 3.72%, respectively) of bread and durum wheat rather than tolerant ones (2.21% for Dagdas, 1.57% for Meram compairing to their controls 4.12% and 5.88%, respectively) at the 48 h of salt treatment. Calculated nuclear volume of wheat genotypes besides Dagdas showed a decline at the 48 h ranged from 1.57 x 10(5) to 2.13 x 10(5) mu m(3). Vacuolization and nuclear distortion appeared on DAPI-stained preparations. There was a clear reduction in starch content in salt treated genotypes of durum wheat.