The function of vitamin B9 (folic acid) on mitotic activity and chromosome behaviors in meristematic cells of barley (Hordeum vulgare L. cv. 'Bulbul 89') seeds germinated at different salt concentrations were studied. The prohibitory impact of salinity on mitotic index significantly increased in parallel with increase of salt concentrations as compared to control group. The mitotic inhibition was 33.3% at 0.35 M salt concentration. Furthermore, the mitotic inhibition reached the lowest value (46.6%) after treatment with folic acid alone. The frequency of chromosome aberrances in meristematic cells of barley seeds treated with folic acid alone demonstrated a marked increase (approx. 32%) compared to the control seeds. The frequency of aberrances were gradually increased with increasing salt concentrations. In addition, folic acid pretreatment was statistically ineffective in recovering of the unfavourable effect of different salt concentrations on mitotic activity while it reduced the harmful effects of salinity on chromosome aberrances particularly at high salt concentrations.