Background and Objective: Self-efficacy is defined as a belief in one’s capabilities to cope with stressful situations and execute a specific coping behavior. Previous researches verify the efficiency of childbirth preparation classes as one of the convenient methods in helping women to deal with labor pain the most severe pain that women may experience in their lifetime. This study was carried out to determine the effectiveness of childbirth preparation classes on self-efficacy of pregnant women in coping with labor pain in Zanjan province. Materials and Methods: This quasi-experimental case –control study was carried out on 60 subjects who were randomly assigned to two equal groups of 30. The case group comprised 30 pregnant women who attended to childbirth preparation classes whereas the control group received only standard antenatal care. Questionnaires were completed through face to face interviews one hour after the delivery in postpartum delivery room. To determine the effect of childbirth preparation classes on self-efficacy in delivery of pregnant women, childbirth self-efficacy inventory and attitude questionnaire was used. Results: Mean scores of self-efficacy in the control and case groups were 221.5±65.86 and 241.7±61.68 respectively. Despite higher self-efficacy scores in the case group, the difference between the two groups was not significant as indicated by independent t-test. Conclusion: This study supports the substantial effect of childbirth preparation classes in perceived self- efficacy of pregnant women in delivery.