There has been an increase of anti-ulcer drug consumption in Spain. A high proportion of this consumption may be due to the use of those drugs as gastroprotective agents when co-prescribed with non-steroidal anti-inflammatory drugs (NSAIDs). The aim of this study was to learn how these treatments are being used: the prevalence of use, the type of drug and the main features of patients. A sample of patients going to pharmacies with a NSAID prescription, with or without a gastroprotective agent, was obtained. A survey questionnaire was distributed to learn clinical and demographic data of the patients. Of the 942 patients interviewed, 41.6% were co-treated with a gastroprotective agent in addition to the NSAID. Most of these patients received proton-pump inhibitors and, to a lesser extent, histamine-2-receptor antagonists, antacids and prostaglandin analogues. The use of gastroprotective agents increased with age, treatment duration and illness chronicity; specialists prescribed a higher proportion of those co-treatments than did general practitioners. There was a high prescription rate of gastroprotective agents; in general, these were used according to recommendations. However, the type of gastroprotective agents being used does not seem to be justified by the current guidelines: histamine-2-receptor antagonists and antacid drugs have not proved their efficacy in this indication. The fact that one in four treatments with gastroprotective drugs was issued to patients without associated risk factors identifies a possible problem where an intervention could be appropriate.