This study has approached the level of knowledge of the community of Vila Isabel on dengue fever and compulsory notification aiming to analyse the factors that have influenced such a notification because, according to SES, dengue is a fever disease of viral ethiology and of benign evolution, in most of cases, being obligatory the notification of suspect or confirmed cases. For the research, the descriptive method and the technique of clinic and social investigation have been applied. During Sep. 91 and Oct. 91, 120 inhabitants from the suburb of Vila Isabel, Rio de Janeiro District, were interviewed. They were mainly of 35 years old or over, female, medium social class, beholders of uncomplete "1º grau" Degree, dewellers in adequate basic sanitation conditions. The majority hadn't contracted dengue fever and got "good" as a conceipt as to their knowledge about dengue fever. However, it was (very bad) their knowledge about the compulsory notifiation, being necessary, thus, a wide diffusion about the prophylactic measures and about dengue fever control