Drug advertisements for prescription drugs gathered from private clinics and hospitals in southern Brazil were analyzed. None of the 127 advertisement inserts that were analyzed complied with all the criteria specified by Brazilian legislation. The official Brazilian generic drug name was present in 95% of the advertisements, but always in finer and/or fainter print. With regard to the "WHO ethical criteria for medicinal drug promotion" the study showed that only 59% of the advertisement inserts declared the product composition and only 43% provided information on precautions, and in most of these cases (73%), the precautions were in fine print and difficult to read. Most of the advertisements declared the product dosage in more properly-sized print. The main advertising claims were efficacy, safety, faster action, and high tolerability. In conclusion, the analysis demonstrated that most advertisements fail to comply with either the Brazilian legislation on medicinal products and/or the WHO ethical criteria for medicinal drug promotion. To improve this situation it thus seems necessary to develop more effective instruments to monitor quality of information provided to prescribers by the drug advertisers.