Objectives. To determine the level of knowledge, proper attitudes and safe sex practices regarding the Human Immunodeficiency Virus (HIV) infection in Peruvian women ages 15 to 49 years. Materials and methods. We used the results of the Continuous 2004-2007 Peruvian Demographic and Health survey (DHS). The dependent variable comprised the level of knowledge and attitudes regarding the disease and safe sexual practices. Descriptive statistical analysis and logistic regression was performed to find association between variables. Results: A good level of knowledge about sexually transmitted infection (including HIV infection) was found in 47.8% of women from the population surveyed; 50.7% showed proper attitudes in relation to the disease and the people affected by it, while safe sexual practices were observed in 48.8% of the persons surveyed. Higher educational level, high index of socio-economic welfare, residence in the capital city during childhood, working as professional, technical, business women or clerical position; and frequent media access, were related to greater knowledge, good attitudes and safe practices. Conclusions: The level of knowledge, attitudes and practices shown by 15 to 49 year old Peruvian women regarding sexually transmitted infections is not adequate.