Aims: This study aimed to estimate the prevalence of driving after drinking (DUI) and its associated factors in low and high alcohol outlet density areas (LAOD and HAOD) in Porto Alegre, Brazil. Methods: A probability 3-stage sampling survey was conducted, and 683 drivers who were leaving alcohol outlets (AOs) and had been drinking were interviewed, breathalyzed and saliva was collected for drug screening. Prevalences were assessed using domain estimation and DUI predictors were assessed using logistic models. Results: It was estimated that 151,573 drivers drank at the AO, and intention to DUI was more prevalent in LAOD (59.3 versus 46.1% in HAOD, P = 0.003). On the other hand, HAOD had higher proportions of interviewees with a blood alcohol concentration (BAC) of >0.06% (46.6 versus 30.7%, P = 0.002) as well as a more frequent use of cocaine (9.3 versus 2.4%, P = 0.086). In the logistic models, drinking in a LAOD stratum was found to be associated with DUI (OR 1.72 (1.17 – 2.5)) and the two AO density areas presented different factors independently associated with DUI: THC use was significantly associated with the outcome in the HAOD stratum (OR 17.7 - 5.1 – 61.8)), whereas an AUDIT score of >20 was positively associated with DUI in LAOD (OR 23.75 (1.5 – 364.0)). Conclusions: High prevalences of driving under the influence of alcohol were evident in both the high and the low outlet density areas, although with different characteristics. Thorough enforcement of the legislation by random breath testing and sobriety checkpoints should be combined with AO licensing in order to reduce high levels of DUI and traffic accidents.