In order to obtain information on prescribing habits concerning the prevention of gastroduodenal lesions induced by non-steroidal anti-inflammatory agents (NSAI), 356 physicians practicing in 2 French departments were asked to fill a posted questionnaire. Fifty-one percent of these doctors gave an assessable answer. Among these, 84 percent occasionally prescribe "gastric protectors" associated with NSAI's in 32 percent of the prescriptions. They use antacids (48 percent), anti-H2 products (27 percent), sucralfate (11 percent) or prostaglandins (13 percent). This represents a daily cost of additional treatment ranging from 0.87 to 2.49 francs. If fibroscopies and further consultations necessitated by the prescription of NSAI's are taken into account, then 86 to 140 percent must be added to the cost of NSAI's. The profitability of these preventive measures in terms of public health will be really estimated only when the number of severe gastroduodenal lesions effectively prevented by taking topical gastric protectors or anti-secretory agents will be known.