Educational campaigns to inform the population about dengue fever, vectors, and related control measures have been carried out since 1985 by health services. In order to assess knowledge levels in São José do Rio Preto, São Paulo, a household survey was performed with a sample of 537 households in the urban area of São José do Rio Preto, São Paulo, in April and May 1995, where the same number of women were interviewed with questions about dengue fever, vectors, and control measures. Knowledge as displayed was satisfactory, except for that concerning hemorrhagic dengue. However, acquisition of knowledge was not followed by adoption of necessary control measures was insufficient to decrease infestation rates for dengue vectors in the city.