The preparation and screening of antipyretic, anti-inflammatory, analgesic, gastroprotective and antiplatelet activities of original non-acidic aminobenzo-pyranopyrimidine derivatives are described. Major and dose-dependent analgesic and antipyretic properties were detected in all the compounds after oral administration (6.25-100 mg kg-1) in the mouse writhing test and in the E. coli lipopolysaccharide-induced fever in the rat, respectively. Unlike the reference drug indometacin (ED50 ulcer = 9.1 mg kg-1), no gastrolesivity was displayed by all the new compounds up to 150 mg kg-1 so that therapeutical indices equal or higher than that of indometacin were calculated. Furthermore, at 100 mg kg-1 they were able to prevent ethanol-induced gastric mucosal injury in rats. At a 1 mmol/l concentration the compounds under study were as effective as acetylsalicylic acid in inhibiting in vitro platelet aggregation induced by adenosine diphosphate.