Aim: This quasi-experimental study explored application of the self-efficacy theory in improving self-efficacy, communication skills and patient satisfaction among medical interns. Methods: This study was conducted among 70 medical intern students. Being selected by human judgment and homogenous sampling method, participants were assigned into control and intervention groups. Participants in the invention group received an e-book, two one-on-one training sessions and feedback on their shared experiences in group discussions by peers. The Kirkpatrick model was applied to evaluate the intervention. Participants' knowledge, self-efficacy and communication skills as well as their patients' satisfaction were assessed. Data from self and observational assessments were compared in and between groups at different time-points. Results: Participants' knowledge, self-efficacy and communication skills as well as their patients' satisfaction were improved significantly in the intervention group compared to that of the control group. Correlation coefficient between interns' self-efficacy and communication skills scores was 0.74 (P = 0.03). Conclusions: Application of self-efficacy theory could improve medical interns' communication knowledge, self-efficacy and skills leading to patient satisfaction.