The Brody, Gompertz, Logistic and Bertalanffy functions were used to estimate growth in ewe lambs of the Morkaraman and Awassi breeds from birth to 360 days of age. For lamb growth, the Gompertz function resulted in the best fit for the Morkaraman breed, while the Bertalanffy function was best for the Awassi breed. Comparisons between these functions were based on coefficients of determination for the specific model and mean square error showed that the Brody, Gompertz, Logistic and Bertalanffy functions were more appropriate in explaining the growth performance of Awassi rather than Morkaraman lambs. The relationship between models for the parameter estimate of A, B and k in the Morkaraman and Awassi breeds were significant. (C) 2004 Elsevier B.V. All rights reserved.