ABSTRACT -------- - **OBJECTIVES**: In response to the COVID-19 pandemic, many governments worldwide have implemented social distancing policies with different levels of both enforcement and compliance. We conducted an interrupted time series analysis to estimate the impact of lockdowns on reducing the number of cases and deaths due to COVID-19 in Brazil. - **METHODS**: Officially daily data was collected for four city capitals before and after their respective policies interventions based on a 14 days observation window. We estimate a segmented linear regression to evaluate the effectiveness of lockdown measures on COVID-19 incidence and mortality. - **RESULTS**: The initial number of new cases and new deaths had a positive trend prior to policy change. After the lockdown, a statistically significant decrease in new confirmed cases was found all state capitals. Similarly, we find evidence that lockdown measures were likely to reverse the trend of new daily deaths due to COVID-19. In São Luis, we observed a reduction of 37.85% while in Fortaleza the decrease was 33.40%, on the average difference in daily deaths if the lockdown had not be implemented. Similarly, the intervention diminished mortality in Recife by 27.76% and Belém got 16.77%. - **CONCLUSIONS**: Social distancing policies can be useful tools in flattening the epidemic curve.