Brooding of chicks at lover than recommended temperature was reported by Huston (1965) and Harris et al., (1975) to be acceptable when based on growth and feed efficiency of chicks older than 3 weeks of age, while Sainsbury (1980) reported that the best performance will probably be obtained if the house-temperature is reduced from 30 deg ˚C during the 1st week to 27 deg ˚C in the 2nd week and 14 deg ˚C in the 3rd week. Meanwhile, Fender and Sedaneil (1983) mentioned that, the successful, broo ding of chickens requires an environmental temperature in the 24 to 30 deg  ˚C of range during the first 3 to 4 weeks of growing period. Other workers (Huston et al., 1960: Renwick and Washburn, 1982) reported reduced growth, poorer feed efficiency and increased nortaifty of chicks brooded at 26.7 7 deg ˚ C or lower immediately after hatching. In addition, David et al., (1972) mearioned that, meat production fell by 14% in the fi- rat week of continuous residence at ambient (35 deg ˚C) and then remained almost constant for the following 3 weeks. So, in the present investigation an attempt was made to study the effect of cool brooding on the chicks performance under Egyptian environment conditions in winter season, with accidental managemental failure (insufficient heat warming sources).