The Diagnostic Interview for Genetic Studies (DIGS), developed in 1994 by the National Institute of Mental Health (NIMH), was translated into Korean and tested for reliability and diagnostic validity. Concurrent validity was tested using the Structured Clinical Interview for DSM-IV (SCID) and clinical diagnoses in 53 patients, most of whom had either schizophrenia or bipolar disorder. Inter-rater reliability was tested in 24 patients. Test-retest reliability was also tested in 17 patients. Overall and specific diagnostic validity for the Korean version of DIGS (DIGS-K) was excellent for most diagnoses. Inter-rater and test-retest reliability for overall and specific diagnoses also ranged from fair to excellent. For schizoaffective disorder, the test-retest reliability of DIGS-K was in a fair range, although the level was lower than that of other diagnoses. However, its diagnostic validity and inter-rater reliability was below fair range. In conclusion, DIGS-K appears to be a reliable interview for major psychiatric disorders.