Objective: To analyze the trend and impact that COVID-19 had on the notifications of STIs (HIV/AIDS, Syphilis, HBV, and HCV) in Brazil. Methods: This is an ecological study, analyzing the temporal trend of STIs notifications based on the detection rate of infections across the five geographical regions of Brazil from 2015 to 2021. The trend analysis from 2015 to 2021 was conducted using a linear regression model for historical series. To assess the impact of the pandemic, the expected cases were compared with the observed cases for the years 2015 to 2021. A significance level of 5% was established, with trend analyses conducted using the Joinpoint Regression Program, and the expected values were estimated using the R software. Results: The results demonstrate that there was a sharp decrease in the detection rates of mandatory notifiable STIs in Brazil during the COVID-19 pandemic period, and this trend was reflected across all regions of the country. Conclusion: During the COVID-19 pandemic, there was a reduction in STIs notifications. These results support the establishment of surveillance and health care strategies to minimize the impact of delays in the diagnosis and treatment of these infections.