Problems due to alcohol use among drivers have been assessed worldwide and studies indicate high morbidity and mortality rates related to drinking and driving. There are few national studies about this subject. Thus, this study was conducted aiming at estimating the prevalence of drinking and driving and testing the acceptability of passive and active breathalyzers. A total of 908 drivers were tested in the main streets of a city in the state of São Paulo, from February 2005 to March 2006. The methodology adopted was sobriety checkpoints. In 23.7% of the drivers some level of alcohol was found in the exhaled air; in 19.4% alcohol level was equal to or higher than the legal limit. The passive breathalyzer was reliable and presented results comparable to the active one. These findings were six times higher than those found in similar surveys carried out in other countries, indicating the relevance of this problem. Specific public policies to fight the problem and more national studies are needed.