Objectives: No studies have taken a multigenerational approach to the study of oral health inequalities. This study investigated whether grandparents' social class was associated with adult grandchildren's oral health. Methods: Data from the 1958 National Child and Development Study (NCDS) and the 1970 British Cohort Study (BCS) were analysed. Cohort members' occupational social class and persistent trouble with mouth, teeth or gums in the past 12 months were reported at ages 33 years in the NCDS and 26 years in the BCS. Information on grandparents' and parents' social class was reported by the cohort members' mothers during childhood. The association between grandparents' social class and cohort members' report of persistent trouble with mouth, teeth or gums was tested in marginal structural models (MSMs). Results: Data from 9853 NCDS and 6487 BCS participants were analysed. Grandparents' social class was not associated with cohort members' report of persistent trouble with teeth, gums or mouth in the NCDS sample (odds ratios of 1.25 [95% Confidence Interval: 0.95-1.65] for social class IV/V and 1.12 [95% CI: 0.76-1.64] for social class IIINM-M relative to social class I/II) or the BCS sample (odds ratios of 0.98 [95% CI: 0.68-1.43] for social class IV/V and 0.88 [95% CI: 0.67-1.16] for social class IIINM-M relative to social class I/II). Conclusion: This study provided no support for an independent association between grandparents' social class and adult grandchildren's oral health.