OBJECTIVE: To examine the prospective relation between animal companionship and biomarkers of ageing in older people. DESIGN: Analyses of data from the English Longitudinal Study of Ageing, an ongoing, open, prospective cohort study initiated in 2002-03. SETTING: Nationally representative study from England. PARTICIPANTS: 8785 adults (55% women) with a mean age of 67 years (SD 9) at pet ownership assessment in 2010-11 (wave 5). MAIN OUTCOME MEASURE: Established biomarkers of ageing in the domains of physical, immunological, and psychological function, as assessed in 2012-13 (wave 6). RESULTS: One third of study members reported pet ownership: 1619 (18%) owned a dog, 1077 (12%) a cat, and 274 (3%) another animal. After adjustment for a range of covariates, there was no evidence of a clear association of any type of pet ownership with walking speed, lung function, chair rise time, grip strength, leg raises, balance, three markers of systemic inflammation, memory, or depressive symptoms. CONCLUSION: In this population of older adults, the companionship of creatures great and small seems to essentially confer no relation with standard ageing phenotypes.