SETTING AND OBJECTIVE: The International Study of Asthma and Allergies in Childhood (ISAAC) reported asthma prevalence in Peru to be among the highest in the world. We assessed the prevalence and morbidity of self-reported asthma in an underserved, peri-urban area of Lima, Peru, with limited medical access. DESIGN: The study was conducted in the outskirts of Lima from March to May 2011. Five hundred children aged 6–18 years were selected through cluster sampling. Parents completed a modified version of the ISAAC questionnaire. Children underwent spirometry testing. Those with a forced expiratory volume in one second (FEV1% predicted) 680% were tested for reversibility using salbutamol. RESULTS: Of the 500 children selected, 71% participated. The prevalence of asthma was 16.7%. Asthma symptoms were associated with self-reported asthma (P, 0.001); 52.5% of children with asthma had ever used an inhaler (P, 0.001), and 27.1% had never been to the doctor for respiratory problems (P, 0.001). CONCLUSION: We found a high prevalence of self-reported asthma and high morbidity related to asthma symptoms in the previous 12 months among the study cohort. Symptoms were poorly controlled due to limited availability of medication and access to medical services.