Brazil is the only country in the world with over 100 million inhabitants that has a public, universal, and free system for the entire population. It is estimated that those who have health insurance and/or better financial conditions do not use the SUS (Unified Health System), but everyone uses it, whether directly or indirectly, when acquiring medications from popular pharmacies, using vaccines, or when food is monitored through health surveillance systems. Thus, this study aimed to understand the sociodemographic profile of users of the Unified Health System (SUS). An integrative review was conducted in the Latin American and Caribbean Health Sciences Information database (BIREME), as well as in the Scientific Electronic Library Online (SciELO), through the US National Library of Medicine (PubMed) and Web of Science, using the descriptors "Unified Health System," "Health Profile," "Health," and "Health Services." The keywords used were "Sociodemographic" and "User." Among the 38 studies analyzed, a considerable social participation of a total of 4,126,846 participants with different characteristics, such as gender and age, is noted. The review showed that the most regular users in the public sector are female, using hospital services, and aged between 20 and 59 years, and the most common research on user profiles was conducted in the years 2019 and 2021.