OBJECTIVE: To estimate the prevalence of anemia and associated factors in adolescents from the city of Recife in Pernambuco state. METHODS: This is a cross-sectional study, involving a random sample of 256 adolescents of both genders, aged 13 to 18, whose hemoglobin concentrations were evaluated, along with their nutritional status and socioeconomic and demographic characteristics. RESULTS: The prevalence of inadequate hemoglobin concentrations was 10.2% [CI95%=6.7-14.5], reaching levels considered as mild anemia (9 g/dL <hemoglobin <12 g/dL). Female students had lower mean hemoglobin concentrations in all age groups (p<0.001). No association was observed between hemoglobin concentrations and nutritional status (p>0.05), nor with socioeconomic or demographic characteristics (p>0.05). CONCLUSION: Although the prevalence of anemia was low and classified as a mild health problem, preventive nutrition education involving the dissemination of healthy eating habits in schools and encouraging the consumption of iron-rich foods are strongly recommended.