A pot experiment was carried out with tomato (Lycopersicon esculentum Mill.) cv. "Target F1" in a mixture of peat, perlite, and sand (1:1: 1) to investigate the effects of supplementary calcium sulphate on plants grown at high NaCl concentration (75 mM). The treatments were: (i) control (C), nutrient solution alone; (ii) salt treatment (C+S), 75mM NaCl; (iii) salt plus calcium treatment 1(C+S+Ca1), 75mm NaCl plus additional mixture of 2.5 mM CaSO4 in nutrient solution; (iv) salt plus calcium treatment 2 (C + S + Ca2), 75 mM NaCl plus additional mixture of 5 mM CaSO4 in nutrient solution. The plants grown under salt stress produced low dry matter, fruit weight, and relative water content than those grown in standard nutrient solution. Supplemental calcium sulphate added to nutrient solution containing salt significantly improved growth and physiological variables affected by salt stress (e.g. plant growth, fruit yield, and membrane permeability) and also increased leaf K+, Ca2+ and N in tomato plants. The effects of supplemental CaSO4 in maintaining membrane permeability, increasing concentrations of Ca2+, N, and K+ and reducing concentration of Na+ (because of cation competition in root zone) in leaves could offer an economical and simple solution to tomato crop production problems caused by high salinity. (c) 2006 Elsevier B.V. All rights reserved.