An experiment was carried out on 64 mixed sex Californian rabbits in Saudi Arabia to investigate the effects of the combinations of environmental temperatures and dietary crude fibre level on growth performance, feed intake and feed conversion. The animals were divided into 4 groups; 2 were kept under a low temperature of 20°C, while the others were kept under high temperature of 32°C. One of each group under each temperature was given a diet containing 10.77% CF. The others were given a diet in which the CF level was raised to 20.12%. All diets contained 17% CP. Digestibility trials were performed and data on nutrient intakes and outputs, coefficients of digestion and nutritive value were evaluated. Data of all traits were statistically analysed using GLM procedure of the SAS program. Rabbits raised under the low temperature (20°C) and fed the high CF diet had the highest body weight and average daily gain, followed by those fed the low CF under the same temperature. Under high temperature (32°C) rabbits fed both diets had the lowest body weight and average daily gain. A reduction in feed intake along with an increase in water intake was found due to the high temperature with almost no difference between the 2 levels of CF. Heat-stress significantly lowered feed conversion up to 9 weeks of age, while at 11 weeks feed conversion was almost similar in all treatments. High dietary fibre significantly improved the digestibility of CF and EE under both temperatures. Digestibility of each of DM and CP was also raised due to the increase in the dietary fibre, however, the differences were not significant.