The aim of this study was to assess back pain and its relation to physical activity as well as Internet addiction among Polish university students during the COVID-19 pandemic. The research was conducted via the Internet in student groups of three universities in Poland (141 people). Back pain was examined by ODI-The Oswestry Disability Index and NDI-Neck Disability Index. The Polish-language International Physical Activity Questionnaire (IPAQ) was used to assess physical activity and the level of Internet addiction was tested using the Kimberly Young Questionnaire. The respondents mostly suffered from pain originating in the cervical spine. In the study group, only every fifth person had a high level of physical activity. Sex differentiates the level of the measures considered. Sitting in front of the computer affects the pain in the spine. Research results suggest that the pandemic is negatively affecting students. Frequent occurrence of back pain is observed with a simultaneous low level of physical activity. Maintaining regular activity during a pandemic, at least at home, is an indispensable preventive measure for physical health.