We describe the procedures of pharmacovigilance (PV) and pharmacoepidemiology (PE) of drugs in a pediatric hospital. These activities contribute to the detection and registration of adverse drug reactions and to determine the patterns of drug prescription among children attended at the hospital. The PV activities show that there is a relation between an increase in incidence of adverse drug reactions and the prescription of a larger number of drugs. The PE activities reveal that antibiotics are the most frequently prescribed drugs and next are drugs used for gastrointestinal diseases. Since PV and PE activities were initiated at our hospital, they have contributed to a more adequate use of drugs in children. As a conclusion of these activities, it could be that if the PE of a hospital is known, drug consumption can be optimally planned. PV and PE demonstrate that, if polytherapy is not necessary, it must be avoided. Finally, the present guide can be adopted to initiate PV and PE at a hospital.