This experiment was carried out to determine the effects of different levels of protein and electrolyte balance (DEB) on performance, biochemical and haematological parameters in Ross (308) broiler exposed to heat stress. In this experiment, 486, one-day old broilers were used in a completely randomized design with a 3´3 factorial arrangement with 3 replicate for a treatment. The diets were formulated according to NRC (1994) recommendation with protein levels (100, 90 and 80% of NRC recommendations) and electrolyte balance (200, 260 and 320 meq/kg). The birds were exposed to heat stress (34±30C) for 8 hours/day (10:00 to 18:00). The results of experiment indicated that body weight gain was significantly different in starter and in broilers fed containing 260 meq/kg DEB and protein (90%) were significantly higher than those fed other levels of DEB and protein, in all periods (starter, grower and total period). In comparison to 200 DEB, the level of 260 DEB increased body weight gain and feed intake in all periods (p<0.05). Dietary protein levels had no significant effect on body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). Dietary DEB and protein had no significant effect on cholesterol, triglyceride, total protein, albumin, sodium and potassium. The experimental groups did not affect on Haemoglobolin, Haematocrit, hetrophyl, lymphocyte, monocyt and White blood cells counts. The concentration of chlorine was decreased by increasing DEB (p<0.05). As a result, using of DEB 260 meq/kg and medium protein level (90% NRC) for broilers exposed to heat stress is recommended.