Abstract This is a cross-sectional study evaluating the association between zinc deficiency and cognitive decline in 591 community-dwelling older adults living in the cities of Campinas, Limeira, and Piracicaba-SP. Cognitive status was evaluated using the Cognitive Abilities Screening Instrument-CASI-S, considering a decline for scores <23 for those aged 60-69 and <20 for those aged ≥70 years. Among the evaluated cognitive domains, older adults with zinc deficiency had significantly lower mean scores on the memory test (p=0.018). For zinc deficiency, values below 70 µg/dL were considered for women and 74 µg/dL for men. The prevalence of zinc deficiency was 3.9%, and cognitive deficit was 9.4%, being significantly higher in those with zinc deficiency compared with those with normal serum zinc concentrations. In adjusted multiple logistic regression analysis, the factors that remained associated with cognitive decline were zinc deficiency (OR=3.80; 95%CI=1.30-11.12), low schooling level (OR=3.12; 95%CI=1.49-6.50), lack of a partner (OR=1.88; 95%CI=1.04-3.42), risk of malnutrition (OR=3.98; 95%CI=2.36-6.71), and a history of encephalic vascular accident (OR=2.70; 95%CI=1.04-6.98). Zinc deficiency was associated with the presence of cognitive decline in older adults. Actions in primary health care are necessary to prevent the deficiency of this nutrient.