Flumequine, a quinoline compound, is a relatively new synthetic antibacterial agent. The drug is usedas a prophylactic and therapeutic agent for control of colibacillosis and salmonellosis in chickens.Literature on pharmacodynamics of flumequine is relat- ively sparse. Hence, the present work was conductedto gain more explicit information on the possible, if any, side effects of the drug, through studying itspharmacodynamics in chickens, antibacterial and histo-pathological effects. Effects On Isolated Preparations:- In the present investigation, flumequine insmall doses st~mulated the motility of isolated smooth muscles of both the intestine and oviduct of chickens.~anwhile, the drug in large doses, exerted an inhib-nor y effect on the motility of these muscles. Thestimulatory effect of the drug, in small doses, might ~ attributed to a central cholinergic agonist activ-ity. However, the inhibitory effect of the drug, in large doses, appeared to be due to a central choline-rgic antagonist acti vi ty .