As a result of the lack of an adequate regulation, the supply and the use of medicines is irrational in Spain. In order to know the characteristics of the prescription and use of drugs among the elderly, two drug utilization studies were carried out. The first study was an analysis of 981 prescriptions from an outpatient clinic of the Spanish Social Security. The results show that a high proportion of fixed-dose combinations were prescribed and that drugs without any demonstrated therapeutic value are often prescribed for the elderly. The second study was a survey of 389 individuals, randomly chosen among people affiliated with a pensioners' club. The results show that drug use is highly prevalent among the elderly, that many medicines without any demonstrated benefit are being taken, and that potentially harmful drugs were being used by a high proportion of patients without medical follow-up. The prevalence of the use of some particular groups of drugs is also presented.