This study aimed to explore the extent of knowledge of tree species and their uses by agroforestry farmers in the Vale do Ribeira, Brazil, to verify whether gender and age are related to species knowledge in different use categories. The study was conducted using semi-structured interviews, guided tours, direct observation and collection and identification of botanical material. Analyses were based on the frequency with which plants were mentioned. Forty farmers (17 women and 23 men aged 18 to 78 years) were interviewed. There were significant differences in the species richness cited exclusively by each gender; the number of species mentioned by men (36 sp.) was higher than by women (11 sp.). Men exhibited a greater knowledge of such categories as construction, organic matter, fuel, animal feed, technology and beekeeping, whereas there were no significant differences for food, medical and other categories. Age was also a distinguishing factor; younger people mentioned the lowest number of species (74 sp.) compared to adults (163 sp.) and the elderly (150 sp.). The greater number of species mentioned exclusively by men may indicate the existence of specialized knowledge, whereas environmental constraints and the availability of plant resources may limit the knowledge of young people.