The study was carried out in the International GAP Agricultural Research and Training Centre (GATEA) between the years 2010-2014 in Diyarbakır, Turkey. The aims of this study were 1) to compare 8 different models (MG, Dhanoa, Nelder, Wood, CLD, and 2nd-, 3rd-and 4th-degree polynomial) used to describe the lactation curve for Awassi sheep by using 557 completed lactation milk yield records, and 2) to identify the suitable model. In addition, the most effects of birth season, parity, and birth type on the lactation milk yield and parameters on the identified model were investigated. As a result of this study, it was determined that the 4th-degree polynomial (POL4) model is the most suitable. In addition, it was found that all the factors, excluding birth type, have significant effects on the model parameters and lactation milk yield (P < 0.05). © 2019, ALÖKI Kft., Budapest, Hungary.