Objectives. To assess the prevalence of self-medication in the urban adult population. Also to investigate the categories of medicines most used and its motivations. Method. The survey consisted of populational cross-sectional study, conducted between April and May 2010 at the Floriano city. The sample consisted of 552 individuals aged from 20 to 59 years. Results. The prevalence of self-medication considering the intire life of participants was 96.9%. In the last three months before the study, 37% have been self-medicated. The classes of drugs most commonly used were analgesics (34.2%), anti-inflammatory drugs (11%), sexual hormones (7.6%), antibiotics (6.5%) and vitamins (6.5%). The main reason for self-medication was pain (78.6%). Previous experience with the medication was the justification by 84% of the participants. Last year, 80.5% of participants who had any expenses with drugs admitted consuming drugs without prescription. Conclusions. This study showed high prevalence of self-medication in the adult population studied. Pain was the main reason for self-medication, which explains the consumption of analgesics by a majority of respondents. Previous experience with the medication was the main justification for self-medication. This demonstrates the need for preventive strategies in health in order to inform this population about the risks of self-medication and contributes to the rational use of drugs.