Abstract The article aims to estimate the incidence and worsening of back pain (BP) during the first wave of COVID-19 in Brazil, as well as to investigate demographic, socioeconomic factors and associated changes in living conditions. ConVid - Behavior Research, applied between April and May 2020, was used as data source. The number and distribution of respondents who developed BP and those who had a worsening of the preexisting problem, their 95% confidence intervals and Pearson’s Chi-square test were estimated. The odds ratio of developing BP or worsening a preexisting problem was also estimated using multiple logistic regression models. Pre-existing BP was reported by 33.9% (95%CI 32.5-35.3) of respondents and more than half (54.4%; 95%CI 51.9-56.9) had worsened. The cumulative incidence of BP in the first wave of the pandemic was 40.9% (95%CI 39.2-42.7). Being a woman, the perceived increase in housework and the frequent feeling of sadness or depression were associated with both outcomes. Socioeconomic factors were not associated with any of outcome. The high incidence and worsening of BP during the first wave reveal the need for studies in more recent periods, given the long duration of the pandemic.