BACKGROUND/AIMS: We investigated metabolic comorbidity status and patterns of medical institution utilization among breast cancer survivors using medical claims data from the Health Insurance Review and Assessment Service (HIRA). METHODS: Using claims data obtained from the HIRA, we selected breast cancer survivors between 2010 and 2015. Descriptive statistics were calculated to determine the frequency of metabolic comorbidities, as well as to analyze patterns of medical institution utilization in accordance with disease status. RESULTS: A total of 89,953 breast cancer survivors were identified. Among these, 12,364 (13.7%) had hypercholesterolemia, 20,754 (23.1%) had hypertension (HTN), and 11,102 (12.3%) had diabetes mellitus (DM). In particular, more than half of breast cancer survivors older than 60 years had HTN, and other diseases sharply increased beginning at age 50 years. For HTN, a total of 531,292 claims were submitted; more than 80% (n = 473,737) were from primary medical institutions, whereas only 2.4% (n = 12,551) were from tertiary medical institutions. The number of claims submitted for DM was 231,526; those from primary medical institutions accounted for 68.5% (n = 158,566), whereas claims from tertiary medical institutions accounted for 12.0% (n = 27,693). In subgroup analyses, the utilization of secondary and tertiary medical institutions was higher among patients with severe diseases and those diagnosed following their breast cancer diagnosis. CONCLUSION: More than 10% of breast cancer survivors were diagnosed with a metabolic comorbidity. Through analysis of medical institution utilization patterns, we ascertained that a communication system linking secondary and tertiary medical institutions with primary medical institutions is needed.