This experiment was performed to determine the stability of antiblotics in cured bone cement and the antibacterial effect with various the amount of antibiotics mixed in bone cement. Experimental animals were divided into control and antibioticimpregnated groups; 3 each for control, cloxacillin, celospor, kanamycln and panimycln groups. Antibiotic activities were measured by disk diffusion method using Staphylococcus aureus and Escherichla coli as standard organisms. The results were as follows: 1. Bone cement itself does not have antibacterial effect on the growth of Staphylococcus aureus and Escherlchia coli. Antlbiotlc impregnated acrylic bone cement showed antibacterial effects which was stable for 4 weeks. 2. In vitro test, the amount to antibiotics released In 24 hours perlod was proportional to the amount of antibiotlcs mixed in bone cement. 3. The duration of antibacterial effect was also roughly proportional to the amount of antiblotics mixed In bone cement. 4. No antibacterial effect could be measured in control groups. 4. In vivo test, the result was revealed similar patterns compared with the result of “In vitro test”, but the amounts of antibiotics released and durations of antibaterial effect was decreased. No antibacterial effect could be measured in control groups. As a result of this sutdy of this study, It is proved that the amount of antiblotics and the duratlon of antibacterial effect are proportional to the amount of antibiotics mixed in bone cemcnt. The impregnation of antiblotics in acrylic bone cement may be used to prevent and treat Infection in the orthopedic fleld.