The pharmacokinetics of enrofloxacin (KNR) and ciprofloxacin (CIP) in newborn and young rabbits were studied. Rabbits of different ages (1‐, 8‐, 16‐, and 30‐day‐old) were administered, by the intraperitoneal route (IP), a dose of 7.5 mg of cither drug/kg. In 1‐, 8‐, and 16‐day‐old rabbits, blood samples were drawn by cardiac puncture, under light ether anaesthesia, at predetermined times after drug administration. In 30‐day‐old rabbits, serial blood samples were drawn through an arterial catheter. Plasma was immediately obtained and analysed using an IIPLC method. ENR and CIP plasma protein binding was also determined.