A factorial experiment (4×3) was conducted to evaluate the possibility of ameliorating the negative effects of heat stress on nutrient digestibility and some physiological aspects of laying hens by using dietary supplementation with KCl (0.0, 0.8, 1.6 and 2.4%), vitamin E (0.0, 150 and 300 mg/kg) or their combinations. Three hundred and sixty, 20-week-old Hy-Line W-36 pullets were assigned to twelve equal experimental groups. All birds were kept in community battery cages (6 birds per cage), set up in an open-sided laying house, and exposed to a daily photoperiod of 16 hr and managed similarly. Twelve mash experimental diets were formulated to contain metabolizable energy of about 2840 kcal/kg and crude protein of about 18.7%, and offered to pullets during the summer season (20-32 weeks of age). The criteria of response were nutrient digestibility, relative weights of certain lymphoid organs and endocrine glands, antibody titers and some blood parameters of laying hens. Apart from the effect of dietary vitamin E supplementation, feeding the KCl-supplemented diets during the hot climate of the Egyptian summer significantly improved K retention and ether extract digestibility, compared with those of the control hens; however, digestibility of the other nutrients was not affected. Hens fed the KCl-supplemented diets had significantly higher relative weights of lymphoid organs (spleen, thymus and bursa of Fabricius) and thyroid gland as compared to those of the control hens; however, relative weights of pancreas, ovary, oviduct and liver were not affected. Feeding the KCl-supplemented diets significantly increased the blood concentrations of hemoglobin, erythrocytes (RBCs) and leukocytes (WBCs), and the antibody titers as well as blood plasma concentrations of total protein, albumin, Ca, inorganic P, T₃, T₄, K⁺ and Cl^-, and plasma activities of ALT, AST and ALP but significantly decreased blood pH and plasma levels of glucose, total lipids, triglycerides, cholesterol, corticosterone and Na⁺ as compared to those of the control hens; however, blood hematocrit percent was not affected. Regardless of the effect of dietary KCl supplementation, hens fed the vitamin E-supplemented diets exhibited no significant differences in nutrient digestibility of the experimental diets. Laying hens fed the diets containing the high level of vitamin E (300 mg/kg) had significantly higher relative weights of spleen and thyroid gland as compared to those of the control hens and those of hens fed the low supplemental level of the vitamin (150 mg/kg) while relative weights of thymus, bursa of Fabricius, pancreas, ovary, oviduct and liver were not affected. Hens fed the  vitamin E-supplemented diets, particularly with the high supplemental level of the vitamin (300 mg/kg), displayed significantly higher means of blood concentrations of hemoglobin, RBCs, WBCs and hematocrit percent as well as antibody titers and blood plasma levels of total protein, albumin, Ca, inorganic P, T₃, T₄ and Cl^-, and plasma activities of ALT and ALP but significantly decreased blood pH as well as plasma levels of glucose, triglycerides, cholesterol, corticosterone, K⁺ and Na⁺, as compared to those of the control birds; however, activity of AST was not affected.  The effects of the interactions between supplemental dietary KCl and vitamin E were significant on K retention, ether extract digestibility, relative weights of spleen, thyroid gland, pancreas and oviduct as well as most blood parameters while other measurements were not affected. It could be concluded that dietary supplementation with KCl (1.6%), vitamin E (300 mg/kg), either separately or in combination, can be used as an effective tool for alleviating the adverse effects of heat stress on the physiological status of laying hens.