¹Ataturk University, Faculty of Agriculture, Department of Animal Science, TR-25240 Erzurum - TÜRKİYE DOI : 10.9775/kvfd.2021.26864 Th e objective of this study is to estimate the body weight of Morkaraman sheep from body measurements with nonlinear models. Five diff erent models (allometric, logistic, saturation growth, exponential and incomplete gamma) are used to estimate best-fitted model for relationship between body length and body weight of Morkaraman sheeps at diff erent sample sizes. Selected 110 sheeps 3-5 years were scored for body weight, body length, height at wither, chest width and rump width. For determining the relationships with body weight between body measurements, correlation analysis was performed. Th e results of the correlation analysis indicated that the highest relationship according to all sample sizes was between body weight and body length (0.95, 0.90, 0.83, 0.81). Considering all parameters included in the model, the parameter showing the highest correlation with body weight was determined as body length according to all sample sizes. Th e highest correlation was found in 50 sample sizes (r=0.95). According to the small sample sizes (10-20), Logistic and Saturation growth models can be used to determine the body weight by using body length, on the other hand, the Incomplete gamma model is more successful to estimate body weight when the sample size is nearly 30 and 50. Keywords : Body measurements, Morkaraman, Logistic, Saturation growth, Incomplete gamma