Abstract: The effects of drought on water potential, osmotic potential, relative water content of leaves and growth, content of proline, sugars and ion in leaves and roots of Sesaum indicum L. cvs Darab 14 and Yekta were determined. Four weeks after sowing, plants were grown under soil moisture corresponding to 100, 5, 0 and 25% field capacity for next four weeks. Water potential, osmotic potential, relative water content of leaves in both cultivars decreased, fresh and dry masses, proline content, reduced, soluble and total sugars and oligosaccharides increased and polysaccharides decreased with increasing of stress. Na+ content in leaves and roots of both cultivars increased but K+, Ca2+ and K+ to Na+ ratio decreased. The mechanisms of drought tolerance in the sesame may be obtained by production of proline, changes in sugars and ion accumulation for maintenance of suitable pressure potential.