This work was carried out in the Rabbitry of the poultry farm, Animal Production Department, Cairo University, Giza, Egypt, during the period from September 97 till August 98. Forty New Zealand White (NZW) does were used in this study. Does were individually housed and fed commercial pelleted rabbits ration. Twenty does were used in cold season and other twenty were used in hot season. Does were divided in both seasons into two equal groups according to reproductive status (non-pregnant and pregnant does). The effects of climatic fluctuations in air temperature on the thermoregulations reactions (rectal temperature (RT), skin temperature (ST), fur temperature (FT), ear lobe temperature (ET), respiration rate (RR) and pulse rate (PR)) of the does were tested at day time hours, 07:00, 12:00, 17:00 and 22:00 twice monthly throughout the season (6 months). Climatic conditions (ambient temperature (AT) and relative humidity (RH)) were recorded twice weekly throughout the experiment. Values of AT and RH averaged 13-20°C and 55-80% in cold season and 26-30°C and 62-82% in hot season, respectively. Blood measurements (hematocrit (Ht), hemoglobin (Hb), total protein (TP), albumin and glucose were determined twice monthly during the season.  Reproductive performance of does (conception rate, gestation length, litter size and weight at birth, litter size and weight at weaning, pre-weaning mortality and milk yield) was recorded. Thermoregulation measurements (ST, FT, ET and RR) were significantly higher in hot than cold season. FT, and ET were significantly higher in pregnant than in non-pregnant does. The determination of pulse rate had no trend due to seasonal variation in pregnant and in non-pregnant does. Ht%, Hb, TP and Albumin reduced significantly as AT increased during hot season for non-pregnant and pregnant does, while the level of level of glucose in serum increased with elevation of air temperature. Reproductive performance of does, generally, was better in cold season than in hot season, except conception rate was higher in hot season than in cold season. However most differences in reproductive performance due to seasonal variation were not significant.