Stigma is one of the common problems of patients with bipolar disorders, which impedes their recovery. This is a quasi-experimental study on 76 hospitalized patients with bipolar disorder (38 in each group) in Iran. The intervention group received six sessions of psychoeducation in a period of 2 weeks. Internalized stigma was measured by the Internalized Stigma of Mental Illness scale. The education significantly reduced the scores of alienation, discrimination experience, stigma resistance and total score of stigma in the intervention group. Hence, this education can be used as an accessible technique in hospitals to reduce the internalized stigma.