Introduction: Promoting and maintaining breastfeeding is an important part of the healthcare, nutrition and other social measures required to promote proper growth and development of infants, and a major component of primary healthcare. Several factors affect onset and duration of breastfeeding. Self-efficacy is one of those factors that can be modified, but has been less studied. Objective : The present study aimed to determine some risk factors associated with breastfeeding self-efficacy of mothers within 6 weeks of delivery. Materials and Methods : This cross-sectional descriptive-analytical study recruited 767 mothers presenting to Family Health and Research Center in Rasht in 2013, using consecutive sampling (for 6 months).Data was collected using demographic questionnaires and Dennis Breastfeeding Self-Efficacy Scale (BSEF).Data was collected in two phases: on the 3 rd -5 th days and the 6 th week after delivery. The minimum and maximum breastfeeding self-efficacy scores in BSEF are 14 and 70, respectively. If a subject's score is above average, she has high breastfeeding self-efficacy and vice versa. Descriptive statistics (mean, standard deviation) and inferential statistics (chi-square test, Mann-Whitney test, Pearson’s correlation coefficient and multiple regressions) were used to analyze the data. The confidence interval of 95% and a significance level of P<0.05 were considered. Results: The results showed that the mean and standard deviation of breastfeeding self-efficacy score were 57.64±9.94 and 62.66±7.57, respectively on the 3 rd -5 th days and the 6 th week after delivery. The group that exclusively breastfed their newborns had higher than average breastfeeding self-efficacy scores compared to other mothers. The multivariate regression model showed that the variables of educational level (secondary school P=0.002, B=2.25; and high school diploma, P=0.03, B=1.51), pain (P=0.01, B=1.6), breastfeeding discontinuation because of pain (P=0.02, B=2.67), having a successful breastfeeding experience (P=0.01, B=1.93), and exclusive breastfeeding (P=0.01, B=6.28) had statistically significant relationships with breastfeeding self-efficacy. Conclusion: According to the results, breastfeeding self-efficacy influenced the status and type of breastfeeding, hence, necessary interventions should be made to remove the barriers to and resolve the problems of mothers for exclusive breastfeeding.