This study compared four nonlinear models to describe growth parameters of broiler chicken fed on different levels of corn bran. Two experiments were designed for this purpose. In the first experiment, 80 chickens (308 Ross strain) that had been fed on the same diet and weighed separately were used to determine the best model. Indicators of R 2 , ACI and the number of circulation of the model were used to confirm the best model. In the second experiment, 300 one-day-old Ross 308 broiler chickens were used in a completely randomized design with four treatments and five replicates. The treatments included control and diets contained 2.5, 5 and 7.5% corn bran. Results showed that the Gompertz function had the highest R 2 and the lowest AIC and number of iterations. So, the Gompertz model best described the broiler growth curves. R 2 , AIC values and number of iterations of the Gompertz model were 0.9970, 648 and 5, respectively. Different levels of corn bran significantly affected mature body weight (W f ) and body weight at the inflection point (W i ) (P<0.05), but did not affect the initial body weight (W 0 ), inflection point (T i ) and coefficient of relative growth (b) (P>0.05). Additionally, corn bran significantly decreased the growth rate on days 21, 28, 35 and 42 (P<0.05), but had no significant effect on the growth rate on days 7 and 14 (P>0.05). Overall, the results showed that the Gompertz model described the biological curves of broiler fed on corn bran better than other models. Also, growth parameters were affected by corn bran.