Recently Seegers et al, (1979) re­ported that concurrent administration of paracetamol with aspirin resulted in decreased gastric acidity indueed by aspirin in rats, this effect is due to stimulation of endogenous production of prostaglandins produced by para­cetamol. The work of Seegers et al. (1979) was based on the observations of Bobak et al. (1978) and Me Donald et al., (1979) that paracetamol could stimulate the prostaglindin sythetase of bovine seminal vesicles in vitro. The antagonism of paractamol to the gastric hyperacidity, may be ac­companied by an antagonism to the therapeutic efficacy of aspirin but, on the other hand, paracetamol has phar­macological properties which are simi­lar to those of aspirin and might there-forefore augment the therapeutic efficacy. In the present work the inter-177 action between paracetamol and aspi­rin with regard to their analgesic and anti anflammatory activities were stud­ied in rats.