Background: Suicide is one of the leading causes of death among adolescents and young adults worldwide. However, risk factors for suicidal thoughts might change across cultures and contexts. We aimed to assess the prevalence and associated factors of suicidal thought among adults in a southern Brazilian city. Methods: This population-based cross-sectional study used a multistage sampling procedure to evaluated individuals with 18 years or more, living in a southern city in Brazil. We collected suicidal thought using a question from the Patient Health Questionnaire-9. In addition, we collected information on sociodemographic, behavioral, and health variables, through a questionnaire using standardized and validated instruments. We calculated prevalence ratios (PR) using Poisson Regression models with robust adjustment of the variance. Results: We collected information from 1295 individuals, 6.6% were positive for suicidal thought. In multivariate analysis, factors independently associated with suicidal thoughts included: being a woman, poor, reporting current tobacco use, having household food insecurity, having three or more morbidities, being in the upper tertile of the stress scores, having had a depression diagnostic in the last year and sadness. Limitations: We cannot say that the associations found are causal. Suicidal thoughts were assessed from a single question. Conclusion: Suicidal thought is a prevalent condition, most likely associated with being a woman, having worst socioeconomic conditions, a poorer health, a higher stress, using tobacco and having depression and/or sadness.