This study was conducted to investigate the effect of early life heat conditioning on some physiological parameters in New Zealand White (NZW) rabbits. Animals were divided into four groups with five replicates, in each replicate six kits (4 x 5 x 6), the first group kits were taken from litter of control does (control), the second group kits   were taken from litter of does were exposed to heat conditioning at day 15 of pregnancy (36±1°C for 6 hrs), the third group were taken from litter of control does, and were exposed to early age heat conditioning (36±1°C for 6 hrs) after birth and the fourth group were taken from litter of does were exposed to heat conditioning at day 15 of pregnancy (36±1°C for 6 hrs) at day 15 of pregnancy and were exposed to early age heat conditioning (36±1°C for 6 hrs) after birth. Red blood cells (RBCs), White blood cells (WBCs) and Hemoglobin (Hb) values were greater on rabbits in fourth group than the third and second groups compared with the lowest values in control group. Rectal temperature and the level of Cholesterol and Corticosterone of rabbits in the 16 week of age under hot summer season in the control group were greater than that in other groups. Early age heat conditioning of all treated groups caused significant (p<0.05) decreased in liver functions (plasma ALT and AST activity) and Kidney functions (urea and creatinine levels). Total antioxidant capacity, Catalase in plasma and Heat shock proteins 70 (HSP70) of all treated groups were higher than in the control group. Body weight and body weight gain at 8, 12 and 16 weeks in kits of heat exposure groups than in the control group. In conclusion, early age heat conditioning of rabbits kits post, pre birth or together led to the improvement in post weaning growth and in thermo-tolerance during the summer season in rabbits.