Objectives: The aim of this study was to investigate the effect of counselor self-disclosure on clients’ perception of counselor's social influence including expertness, attractiveness, and trustworthiness in genetic counseling sessions for thalassemia prior to marriage. Method: This research was an analogue study performed using simulated genetic counseling sessions with depicted scenario. Among couples referred to Isfahan Medical Genetics Center, 131 people participated to the study. We used a demographic questionnaire, a scenario of a genetic counseling session for thalassemia, and Counselor Rating Form-S (CRF-S). Three versions of the scenario were prepared: without counselor self-disclosure, with professional self-disclosure, and with personal self-disclosure. Imaginating themselves as the client, participants completed CRF-S and showed their perception of counselor's social influence. A multivariate analysis of variance (MANOVA) was used to analyze the data. Results: Participants assessed the counselor in the personal self-disclosure scenario more trusted than in scenario without self-disclosure. Conclusion: As shown in previous studies, counselor self-disclosure may have positive effects on clients’ perception of counselor’s social influence.