Breast milk not only protects the health in childhood, but also provides human health throughout life (1). There is definite evidence about both short-term and longterm health benefits of breastfeeding for mothers and infants (2-8) and also its positive effects on increasing the binding and attachment between mother and infant and decreasing family costs. Avoiding breastfeeding is responsible for 45% of children mortality as the result of infection, 30% as the result of diarrhea, and 18% because of acute respiratory problems (9). Despite the supports of national and international organizations, most mothers stop breastfeeding before their infants achieve 6-12 months (10). Unfortunately, the prevalence and duration of exclusive breastfeeding have decreased in recent years (11). According to statistics, in 2010 in East Azerbaijan province, Iran, only 58.76% of newborns, in their first 6 months of life, have been exclusively breastfed by their mothers (12). Self-efficacy is defined as an individual's beliefs in his capabilities in order to implement a definite way for achieving specific goals (1). Breastfeeding self-efficacy is originated from one of the structures of Bandora's socialcognitive theory (1977) and includes the individual's confidence and belief in his capabilities in implementing health behaviors such as successful exclusive breastfeeding. According to Dennis, there is a significant relationship between promoting mother's breastfeeding self-efficacy and the increase of breastfeeding duration (13). Breastfeeding self-efficacy depends on the mother's capability and self-confidence for breastfeeding and affects her decision for continuing it (14). It is one of the predictors of breastfeeding that shows mother's stability in continuing breastfeeding and her attempt to reach it (15,16). Several factors such as young maternal age, educational level, lower income, full-time working, smoking, C-section (17), postpartum depression, anxiety and breastfeeding problems like mastitis can reduce breastfeeding selfefficacy (18-20). A study in Indonesia showed that self-efficacy affects breastfeeding (21). Moreover, another study on pregnant women above 18 years old, in their 37 weeks of pregnancy, showed that mothers with high self-efficacy had high exclusive breastfeeding in comparison with the mothers with low self-efficacy (1). According to the studies in Iran, unfortunately almost half of the Iranian mothers had low breastfeeding self-efficacy; as in the study by Varaei et al (1), 44% of mothers, and in the study by Rahmatnejad et al (22), 49% of mothers had low breastfeeding self-efficacy. However, the very low breastfeeding self-efficacy was Abstract Objectives: Determining the effective factors on breastfeeding self-efficacy can be helpful in designing the promoting interventions for this behavior. The aim of this study was to evaluate the predictors of breastfeeding self-efficacy in mothers referred to health centers of Tabriz, Iran, in 2015. Materials and Methods: This cross-sectional study was conducted on ...