Objective: We examined the sociodemographic factors associated with smoking risk perceptions (SRP) in youth living in two very different neighborhoods in the city of São Paulo, Brazil: a middle-class central area (Vila Mariana) and a poor outer-city area (Capão Redondo). Methods: A cross-sectional survey was conducted with 180 public school-attending youth (all aged 12 years) and their parents. SRP was evaluated through self-reports. Weighted multinomial logistic regression was used to examine factors associated with SRP. Results: Smoking was considered a high-risk behavior by 70.9% of adolescents. There were significant differences in SRP associated with socioeconomic status (SES) and maternal smoking status. Having a non-smoking mother was positively associated with perceiving smoking as having low to moderate risk versus no risk (OR=3.91 [95%CI 1.27-12.02]). Attending school in Capão Redondo was associated with perceiving smoking as having high risk compared to no risk (OR=3.00 [95%CI 1.11-8.12]), and low SES was negatively associated with perceiving at least some risk in smoking versus perceiving no risk in this behavior. Conclusions: Youth whose mothers smoke appear to have lower SRP than those whose mothers do not smoke. Living in a poor outer-city area was associated with higher SRP.