Penicillins are bactericidal antibiotics and bacterial wall inhibitors. Classic penicillins are produced by fermentative cultivation, but semisynthetic penicillins are produced by chemical synthesis from 6 - aminipenicillinic acid. Most bacterial resistance mechanisms are known. We have good knowledge about pharmacodynamics and pharmacokinetics of penicillin antibiotics. Knowledge of penicillin antibiotics characteristics help us in proper management of antiinfective therapy. Antibacterial spectrum of penicillin antibiotics combination with inhibitors of bacterial betalactamase enzymes is broader then penicillin antibiotics alone. Classic as well as semisynthetic penicillin antibiotic are important part of antiinfective drugs.