--Introduction. Generally, in Iran, citrus cultivars are grafted on Sour orange rootstocks. However, susceptibility of this rootstock to tristeza (CTV) has required a research program to replace Sour orange trees with other rootstocks. Materials and methods. Yield performance and fruit quality of Ruby Red and Marsh grapefruits were assessed for 5 years (1999 to 2003) in the Agricultural Research Station in Dezful (Southern Iran) according to the eight different rootstocks used: Carrizo citrange, Citrus amblycarpa, Cleopatra mandarin, King mandarin, Sour orange, Swingle citrumelo, Troyer citrange and Volkamer lemon. Results and discussion. For the 5 years studied, cumulative yields per tree and yield per trunk cross-section area were the highest on Cleopatra mandarin, Sour orange, Swingle citrumelo and Volkamer lemon, whereas trees on Citrus amblycarpa, Carrizo citrange, King mandarin and Troyer citrange were the least productive. The results showed that individual fruit weight, size and skin thickness were significantly higher for both cultivars on Volkamer lemon, compared with the other rootstocks. Fruits on the Cleopatra mandarin rootstock had the lowest weight and fruit diameter. The rootstock type also affected the fruit juice amount and soluble solid content. Fruits from cultivars which were grafted on Sour orange rootstock had total soluble solids of 9.93% and 51% of juice content, whereas on Volkamer lemon rootstock, they had 7.81% of total soluble solids and 45.3% of juice content. Total acid of the fruits from cultivars grafted on Volkamer lemon had the significantly smallest amount (1.33%). In both cultivars of grapefruits, no significant differences were observed except in the size of the fruit, fruit juice and vitamin C contents. Interactions between rootstock and cultivar were significantly different. Conclusion. Our results indicated that the yield and fruit quality of grapefruit are strongly influenced by the rootstock used. Also, the interaction between cultivars and rootstocks may be an interesting strategy for the adaptation of cultivars to different climatic areas. Les résultats ont montré que le poids du fruit, ainsi que la taille et l'épaisseur de la peau des fruits des deux cultivars de pomelo étaient sensiblement plus élevés sur les arbres greffés sur Citrus volkameriana que sur ceux greffés sur les autres porte-greffes. Les fruits sur mandarinier Cleopatra ont eu les poids et les diamètres de fruits les plus bas. En outre, le type de porte-greffe a affecté la quantité de jus de fruit et la teneur en solide soluble. Les fruits des cultivars greffés sur oranger amer ont eu des taux de solides solubles totaux de 9,93 % et une teneur en jus de 51 %, tandis que, sur le porte-greffe Citrus volkameriana, ils ont eu 7,81 % de solides solubles totaux et 45,3 % de jus. L'acidité totale des fruits des cultivars greffés sur Citrus volkameriana a eu les valeurs les plus faibles (1,33 %). Pour les deux cultivars de pomelo, aucune différence significative n'a été observée, exceptés la taille d...