Many bacterial infections can be treated successfully with antibiotics.from the several hundred naturally produced antibiotics that have been purified,only a few have been sufficiently non-toxic to be of use in medical practice.Cephalosporins are the most prescribed antibiotics because they are among thesafest and the most effective broad-spectrum antimicrobial agents.The present work was performed on antibiotic drug (Cefoperazone) andPhytonadione(vitamin Kl) to study side effects for each drug alone and effectof Phytonadione (vitamin Kl) in minimizing side effects caused byCefoperazone if present.This study was carried out on forty male rabbits (2-2.8 Kg body weight)which were divided into 4 groups (1-4). Each group contained 10 rabbits.