The aim of this study was to evaluate the effect of increasing incubation temperature of Araucana hen eggs on embryo mortality, hatchability, chick, yolk sac and internal organs weight. Eggs (n=426) were randomly distributed into: a) Control group (n=215), which were incubated at 37.5 degrees C for 21 days or b) Experimental group (n=211), which were incubated at 39.5 degrees C, for 18 days and then at 37.5 degrees C for the remaining 3 days. In both groups eggs were incubated with a relative humidity of 55 %. The embryo mortality rate was greater (P <= 0.05) for the experimental than the control group (44.1 vs. 14.9 % respectively). On the contrary, hatching rate was greater (P <= 0.05) for the control than the experimental group (97.8 vs. 80.5 % respectively). The average weight of chicks, at 36 h of age, was lower (P <= 0.05) for the experimental than control group (36.3 vs. 37.01 g respectively). Also, increasing incubation temperature reduced (P <= 0.05) internal organs weight of chicks in the Experimental compared to Control group. On the other hand, yolk sac weight was reduced (P < 0.05; 2.5 vs. 6.2 g for Control and Experimental group respectively). We conclude that increasing the incubation temperature of Araucana hen eggs up to 39.5 degrees C for 18 days has a negative effect on embryo survival, hatchability, chick and internal organs weight and absorption of yolk.