Introduction and Objective.The results of the Health Behaviour in School-aged Children (HBSC) surveys conducted in 2018 and 2022 allow for a comparison of selected health-related indicators from before the COVID-19 pandemic and from its final phase. The aim of the study is to assess the level of health literacy (HL) among Polish students aged 13-17 years. Materials and Method. The surveys were conducted with nationwide samples of students (N2018=5648 and N2022=4994, respectively). Changes in the overall HLSAC-5 index and its five dimensions were examined. Results. The findings indicate a significant decline in the average HLSAC-5 scores from 15.35±2.40 to 14.84±2.80, alongside an increase in the proportion of students with low HL from 9.85% -23.67%. Concurrently, the percentage of students rating their health as poor rose from 3.5% to 9.1%. An increasing disparity in HL levels across schools was also observed, with the intraclass correlation coefficient (ICC) escalating from 3.4% to 6.1%. General linear model confirmed a significant influence of gender, age, place of living, family affluence, self-rated health, and eight significant 2-way or 3-way interactions between independent variables. Notably, there were five significant 3-way interactions involving the year of the survey and self-rated health, with the third factor, gender, age, family wealth, presence of a chronic disease, and place of residence, respectively. Conclusions. The study highlights the dynamic nature of HL and its evolving relationship with various socio-demographic and health factors over time. The changes in students' HL may have been influenced by factors related to living and learning during the COVID-19 pandemic.