Due to the COVID-19 pandemic, theWorld Health Organization and other major authorities recommend frequent hand washing and applying proper hand hygiene procedures as one of the cheapest, easiest, and most important ways to prevent the spread of a virus . For adolescents it is especially important as it should become for them a lifelong habit . The aim of the study was to assess the hand hygiene behaviors during the COVID-19 pandemic in a national Polish sample of secondary school adolescents and to verify the influence of the COVID-19 pandemic on those behaviors . The study was conducted in April 2020 in a national sample of 2323 secondary school students recruited based on secondary school sampling procedure (random quota sampling with quotas for voivodeships). The hand hygiene behaviors that were assessed included: frequency of washing hands, reasons for not washing hands, circumstances of washing hands, and procedure of handwashing . Participants were asked each question twice-for the current period of the COVID-19 pandemic and for the period before the COVID-19 issue . The declared frequency of washing hands during the COVID-19 pandemic was significantly higher than before (p <0.0001), as the majority of respondents declared doing it 6-15 times a day (58.4 %) while before the pandemic, it was 3-10 times a day (68.1 %). The share of respondents declaring washing their hands always while it would be needed was significantly higher for the period during the COVID-19 pandemic (54.8 %) than it was for the period before (35.6% ; p <0.0001), and there was a lower share of respondents declaring various reasons for not washing hands . For the majority of circumstances of washing hands, including those associated with meals, personal hygiene, leaving home, socializing, health, and household chores, the share of respondents declaring always washing their hands was significantly higher for the period during the COVID-19 pandemic than for the period before (p <0.0001). For the majority of steps of handwashing procedure, the share of respondents declaring including them always was significantly higher for the period during the COVID-19 pandemic than for the period before (p <0.0001), but a higher share declared not wearing a watch and bracelet (p = 0.0006), and rings (p = 0.0129). It was concluded that during the COVID-19 pandemic all the assessed hand hygiene behaviors of Polish adolescents were improved, compared with those before, but hand hygiene education is still necessary.