Many studies have evaluated the impact of oral inflammatory diseases on muscle strength in the elderly, but previous studies have been limited to cross-sectional designs. To reveal the causal effects of this relationship, we conducted this prospective study. The aim of our study was to determine the association between oral health and baseline grip strength, and the causal effects of oral health on muscle strength after 4 years in an elderly Korean population using nationally representative data. This prospective study used the database from the Korean Longitudinal Study of Ageing (KLoSA). The participants included 6,940 individuals aged 55 years or older. Oral health satisfaction (OHS) was assessed using the General Oral Health Assessment Index (GOHAI), and muscle strength was measured by maximum handgrip strength at baseline and every 2 years during the 4-year follow-up. Multiple confounding factors were evaluated. This study included 2,936 men (mean OHS score 51.4, mean maximum handgrip strength 31.6 kg) and 4,001 women (mean OHS score 51.2, mean maximum handgrip strength 20.2 kg). Baseline OHS was associated with grip strength in both men (β=1.16, P=0.028) and women (β=1.11, P=0.001). Using a mixed-effects model, we found that changes in OHS over the study period were associated with changes in handgrip strength over time in women (β=0.045, P<0.001), and were marginally associated in men (β=0.02, P=0.059). The sarcopenia group at 4 years was associated with poor baseline OHS status in women (adjusted OR 1.41, 95% CI 1.10-1.96).7 Low grip strength not only affects physical function but also has a broader impact on various poor health outcomes in the elderly. This study implicates that maintaining and enhancing oral health is important for preserving muscle function in the elderly. We observed an association between baseline oral health and handgrip strength, and a positive longitudinal influence of oral health on changes in muscle strength in elderly Koreans over 4 years.