Since the significance of metacognition as the theoretical basis of a psychological intervention for schizophrenia first emerged, there have been ongoing attempts to restore or strengthen patients' metacognitive abilities.A Korean version of the metacognitive training (MCT) program was developed, and its effects on theory of mind, positive and negative symptoms, and interpersonal relationships were examined in stable outpatients with schizophrenia.A pre-test-post-test design with a control group was used. The participants were 59 outpatients (30 in experimental group, 29 in control group) registered at five mental health facilities in a city in South Korea. The developed MCT program was applied for a total of 18 sessions, 60 min per session, over a period of 14 weeks. The hinting task, false belief task, Scale for the Assessment of Positive and Negative Symptoms, and Relationship Change Scale were used to verify the effects of this program. Data were analysed by the chi-square test, t-test, and Mann-Whitney U-test using the SPSS/PASW 18.0 statistics program.The general characteristics, intelligence, and outcome variables of the two groups were homogeneous. After the intervention, the experimental group showed significant improvements in theory of mind, positive and negative symptoms and interpersonal relationships compared with the control group.These results suggest that the MCT program can be a complementary psychotherapy that contributes to symptom relief and interpersonal functioning in patients with schizophrenia, and is effective in the Korean culture, beyond the Western context.