Some perinatal factors have been associated with attention d ficit/hyperactivity disorder (ADHD).To estimate the association between perinatal factor and ADHD diagnosis in school, aged 6 to 11 years, children from Medell n city (Colombia).A randomized sample of 200 cases, 6 to 11 year old, with standardized ADHD diagnosis was selected. A randomized sample of 200 control children, 6 to 11 year old, was selected from a data base of 70 schools of Medell n city. The same diagnostic protocol was administered to controls. A questionnaire with questions about pregnancy, delivery an neonatal period was given to the mothers. Data were analyzed using cross tabulation and stepwise logistic multiple regression analyses.Miscarriage symptoms, premature delivery symptoms, severe flu attacks (cold with fever, without virus confirmation), tobacco abuse, alcohol abuse (to become drunk), minor congenital malformations, neonatal seizures and hospitalizations during newborn period were factors associated with ADHD diagnosis (p< 0.05). However, stepwise logistic multiple regression analysis selected a block of variables formed by premature delivery symptoms, severe flu attacks and neonatal seizures as significant perinatal risk factors (p< 0.01) for ADHD diagnosis.