The effects of cadmium sulfate on cadmium accumulation and phytochelatin synthesis were investigated in leaf, stem and root tissues of two sunflower cultivars, cadmium tolerant Helianthus annuus cv. Meric and sensitive Tarsan 1018. The seedlings were grown for 15 days in Hoagland solution and then exposed to CdSO(4) at 150 mu M, 200 mu M, 250 mu M and 300 mu M for 4 days. Most cadmium accumulations were determined in the roots of both cultivars on the 2(nd) and 4(th) day. The cadmium sensitive cultivar, Tarsan 1018, accumulated more Cd in all tissues compared to the tolerant cultivar. Phytochelatin synthesis was induced by Cd exposure in both cultivars at the 2(nd) and 4(th) day. Higher phytochelatin accumulation was observed in root tissues of Tarsan 1018 cultivar at the 4(th) day. Phytochelatin levels in all tissues of both cultivars increased depending on Cd accumulation in those tissues.