OBJECTIVES: Evidence suggests that while disabling back pain (BP), and rheumatic diseases associated with pain, continues to increase with age, the prevalence of non-disabling BP reaches a plateau, or even decreases, in the oldest old. This study aimed to determine whether this age-related pattern of non-disabling BP is a function of increasing cognitive impairment. METHODS: Cross-sectional study of adults aged >77 years. Participants answered interviewer-administered questions on BP and cognitive function, assessed using the Mini-Mental State Examination, categorised into normal versus mild, moderate or severe impairment. The relationship between cognitive function and BP was examined using multinomial logistic regression, adjusted for age, sex and residence. RESULTS: Of 1174 participants with BP data, 1126 (96%) completed cognitive assessments. The relationship between cognitive function and BP differed for disabling and non-disabling BP. Across categories of cognitive impairment, increasingly higher prevalence of disabling BP was reported, compared to those with normal cognition, although this was not statistically significant (odds ratio (OR) = 1.7; 95% confidence interval (CI) = 0.7-4.6). No association was found between cognitive function and non-disabling BP (OR = 0.8; 95% CI = 0.4-1.6). CONCLUSION: This study found no association between the reporting of BP and level of cognitive impairment, suggesting that increasing cognitive impairment is an inadequate explanation for age-related decline in self-reported non-disabling BP. Future research should determine the reasons for the decline in non-disabling pain in older adults, although, meanwhile, it is important to ensure that this group receive appropriate pain assessment and pain management. KEY POINTS: Prevalence of non-disabling back pain decreases in the oldest old.Some have proposed that this may be a function of cognitive impairment in older age, and an increasing inability to adequately report pain.Our findings do not support this hypothesis.