This study aimed to estimate the prevalence of non-vaccination and the reasons for nonadherence to the influenza vaccine among older Brazilians according to sociodemographic characteristics. A cross-sectional study was conducted with data from older people (≥ 60 years of age; n = 23,815) who participated in the 2013 National Health Survey. Frequencies of non-vaccination and the main reasons for nonadherence were calculated with respective 95% confidence intervals. The prevalence of non-vaccination was 26.9% (approximately 7,106,730 older people). The reason rarely gets the flu was the most cited among the men (28.2%), the 60-to-69-year-old age group (29.6%), individuals with higher education (41.9%), and those with health insurance (32.3%). Fear of a reaction was the most cited reason in the northeastern region (25.4%), among women (29.3%), longer-lived individuals (≥70 years; 28.7%), and those who did not know how to read/write (26.7%). A total of 12.1% reported not believing in the vaccine’s protection, and 5.5% did not know that it was necessary to take vaccine. The proportions of the main reasons for non-vaccination varied by sociodemographic characteristics. This study’s findings highlight the need to increase older people’s knowledge regarding influenza and influenza vaccines. Healthcare providers should be encouraged to counsel older people–especially those in subgroups with lower adherence, such as residents in the Northeast region, those aged 60–69 years, those who do not know how to read/write, those without a spouse/companion, and those without health insurance–regarding the different aspects of the vaccine and formally indicate it for groups at risk.