This study, intended to contribute to the fight against HIV/AIDS infection, sought to identify the factors limiting condom use among the pupils of the El Mina middle school in Nouakchott, in the Islamic Republic of Mauritania. This investigation, conducted in May 2004, concerned 711 students aged approximately 12-16 years. The dependent variable was condom use, and two categories of independent study variables were examined: socio-demographic and HIV information. The data were entered, verified, and analyzed with Epi info 6.04 software. Overall 40% of the students reported sexual activity; in this group, 41% reported multiple partners and 38% unprotected sexual relations. Condom use was significantly more frequent among boys, married students, students with more than one partner, those who attended educational sessions, those for whom sexuality is a taboo subject, those who knew a source of supply, and those for whom condoms were geographically and financially accessible. Condom use among sexually active students is insufficient. This underuse is caused by shortcomings in the distribution system and contributes to the multiplication of sexually-transmitted diseases, including HIV, among the pupils. To provide students with the knowledge necessary for the desired behavioral changes, the following steps are necessary: promoting social marketing of condoms, involving other partners in the fight against STDs and AIDS, using peer educator strategies, and integrating units on HIV/AIDS into secondary education. Given the seriousness and the increasing extension of the HIV infection, condom use should be promoted to improve the sexual and reproductive health of students and thus of the entire population of Mauritania.