The present study describes the results obtained in a screening program aimed at detecting adverse reactions to medication in children aged 1-8 years admitted to the Pediatrics Service of the University of Granada Hospital (Spain). The program is based on monitoring the patients for a period of 12 months. Of a total of 597 patients, adverse reactions were recorded in 4.4%. Within this group the reactions were classified as confirmed in 33.3%, probable in 30% and possible in 36.6%. Based on organs and systems, the CNS was most frequently affected (40%), followed in decreasing order by the digestive (37%) and cardiovascular systems (10%), skin (10%) and endocrine system (3%). The drugs most frequently involved were bronchodilators (40%), antibiotics (30%) and antiepileptics (20%). Among risk factors, polytherapy, hospitalization time and type of drug administered were the most important.