OBJECTS: This study aimed to determine the association between annual medical expenses and oral frailty in later-stage older adults (aged ≥ 75 years). No studies have investigated the association between medical costs and oral frailty, which would elucidate the association between oral frailty and the deterioration of mental and overall physical function. MATERIALS AND METHODS: In this cross-sectional study, 2190 adults (860 men and 1330 women aged 75-94 years) covered by the Medical System for the Elderly and residing in Tottori Prefecture, Japan, between April 2016 and March 2019, were included. Participants were classified into three groups: healthy, pre-orally frail or orally frail, based on dental health screening findings. The medical and dental expenses over the years, number of days of consultations and comorbidities were obtained from the Japanese Health Insurance Claims Database. RESULTS: The number of days of medical and dental consultations and annual medical expenses for outpatient care differed among the three study groups. A significant association was observed between oral frailty and high annual expenses for outpatient medical and dental care. Oral frailty was associated with higher medical expenses in participants with poor masticatory function. Higher and lower dental expenses were associated with subjective poor masticatory function and subjective impairment of swallowing function respectively. CONCLUSION: Medical and dental expenses for orally frail older adults are high, indicating that oral frailty may be related to the occurrence and severity of diseases other than oral health issues. Future studies should examine the mechanism by which oral weakness affects physical and mental functions.