To look out whether patient age influences over the counter active drug prescriptions, simulated structured hypothetical cases of respiratory illness affecting an infant and or a school-age child were presented to staff of 67 pharmacies at metropolitan Santiago, Chile, by a trained interviewer. Answers were recorded immediately after interview in specially designed forms, together with pharmacy's neighbourhood socioeconomic level, adscription to commercial chains of pharmacies or companies as well as gender and profession of the interviewed person. The Fisher-Irwing test for dichotomous variables was used to assess statistical significance. In most cases patient was not referred to a physician 104/134 (77.6%), and a diagnosis was followed by prescription of drugs in all these instances. Antibiotics were often prescribed 67/134 (50%) and the visit to a physician was considered to have been unduly postponed in 74/134 (55.2%) of cases. These outcomes were enhanced by interviewed's male gender and location of pharmacies in medium or low socioeconomic level neighbourhoods. Infants were more often referred to physicians (58% against 3%, p = 1.58 x 10-8) and were prescribed antimicrobials less frequently than schoolage children (96% against 42%, p = 7.7 x 10-9), an outcome that was not influenced by any other included variable. Age less than one year seems to be a protector factor against over the counter drug prescription in these pharmacies.