This study was carried out at the Experimental farm of the New Valley Agriculture Research Station (EL-Kharga Oasis), New Valley, Egypt, during summer season in 2012 and 2013. Four tomato cultivars ['Castle Rock' (CR), 'Strain-B' (SB), 'Super Marmande' (SM) and 'Peto-86' (P86)] were used to determine whether grafting could improve high temperature tolerance. The experiment included 20 treatments (12 treatments were cross-grafts and 4 treatments were self-grafts, in addition, to 4 intact plant treatments). Under the conditions of this study, intact plants of cvs 'SM' and ‘P86' did not survive and their rootstock also neither supported their own scion (self-grafts) nor the alien scions of cvs 'CR' and 'SB' (cross-grafts). The remaining treatments showed that self-grafted plants were superior to their corresponding intact plants especially for early harvesting and total fruit yield. Cross-grafted plants surpassed their corresponding self-grafted plants in all studied traits. Out of the current study, it is advisable to grow the cross-graft 'CR' / 'SB' or 'SB' / 'CR' for production of tomato during the stressful climatic conditions of summer season in the New Valley. The estimated vigor for total fruit yield in these two cross-grafts, respectively, over their corresponding intact plants averaged 148.9 % and 136.2 %.