Background: Older adults constitute a particularly vulnerable demographic regarding SARS-CoV-2 infection. Effective protective measures can substantially lower the risk of transmission. Objective: This study aimed to evaluate the knowledge of COVID-19 vaccines among the elderly in Poland, as well as their reported preventive practices before and after receiving their first dose of a vaccine. Material and methods: This cross-sectional study was conducted between March and April 2021 among consecutive patients aged >=60 from four randomly selected vaccination centers in Zielona Góra, Poland. Knowledge and preventive practices were assessed through an anonymous, self-administered questionnaire. Results: The response rate was 83%, yielding 444 participants (mean age 70.2±4.7 years; 61.0% female), of whom 83.6% reported having underlying health conditions. The average knowledge score regarding COVID-19 vaccines was 3.50±1.72 (on a scale of 0 to 7 points), with 50.7% achieving scores above 50%. Females demonstrated higher levels of knowledge (p=0.008). The mean score for adherence to preventive practices was 5.79±0.66 (on a scale of 0 to 6 points), with 98.9% scoring above 50%. Before vaccination, the vast majority of respondents (93.7%) reported wearing masks, and 89.6% intended to continue this practice after receiving the first dose (p=0.045). Additionally, 66.7% indicated that they would practice social distancing before vaccination. They declared they would continue this practice, rising to 72.8% following immunization (p=0.23). Conclusions: The study suggests implementing national educational campaigns to enhance knowledge of COVID-19, particularly targeting older males and addressing misconceptions regarding vaccine protection to encourage sustained preventive practices.