Background and Objective: In addition to the importance of exclusive breast-feeding (EBF) in the first six months of life, its weaning is also important. This study aimed to determine the pattern of EBF weaning and its associated determinants in Fars province (southern Iran).Materials and Methods: In this historical cohort study, records of 751 infants 6 to 12 months (urban and rural) were selected as multi-random sampling method. Other necessary data were also collected through questionnaires and interviews. In addition to descriptive statistics using statistical tests and survival analysis, the effect of demographic, cultural and labor-related variables on exclusive EBF weaning was also studied.Results: Averaged time of EBF weaning was 4.64±1.68 months and 78.4% of infants have exclusive EBF for 4 months and 50.7% for 6 months. There were not any association between race, official education, sex and birth rank with time of EBF weaning, (p>0.05). Most children (68.5%) began their supplementary food with porridge.Conclusion: Duration of EBF in this study was more than other studies. Lack of significant association between demographic variables, cultural and labor-related variables with duration of EBF, indicated acceptable public health education and lack of wrong beliefs among parents. To promote breast feeding indices, education of parents and breast feeding clinic establishment are necessary.