Objective: to analyze factors associated with the need for dental treatment in adults due to dental caries and tooth loss. Methods: this was a cross-sectional study with a random sample of adults attending Fluminense Federal University School of Dentistry outpatient clinics, in Niterói, RJ, between July and December 2013; we used data collected from clinical records; a questionnaire was administered in interviews; logistic regression analysis was performed to obtain crude and adjusted odds ratios (OR). Results: 212 individuals participated, 71.7% were women; the prevalence of need for dental treatment was 56.1% (95%CI 49.4;62.7); need for treatment was lower in individuals with higher family income (OR=0.53-95%CI 0.28;0.98), and higher in women (OR=2.28-95%CI 1.21;4.32). Conclusion: prevalence of need for treatment in adults was high, especially in women and people with lower family income.