This study aimed to evaluate the Korean version of the M. D. Anderson Symptom Inventory (MDASI-K) as a tool for assessing multiple symptoms in Korean cancer patients. Participants (178 cancer patients and 178 age and sex-matched community-dwelling adults) completed the MDASI-K and the Korean version of the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30. The MDASI-K exhibited substantial reliability and validity. Cronbach alpha coefficients were 0.91 and 0.93 in the cancer patients, and 0.96 and 0.96 in the normal group for both symptom and interference, respectively. MDASI-K summary scores correlated significantly with those of the EORTC QLQ-C30. Discriminant validity of the MDASI-K was demonstrated by its ability to clearly distinguish significant differences within different Eastern Cooperative Oncology Group performance statuses and those between the patient and normal groups in the mean scores of both symptom and interference. The MDASI-K is a valid and reliable measure for assessing multiple symptoms in Korean cancer patients.