Concerning our medical history, the importance of medical terms has been neglected for a long time. In addition, medical terminologies are unaccustomed to the patients including the public. The separation of communications between the public and medical participants has been enlarged more and more. The importance of terms which can be easily recognized, comfortable to the ear, and familiar to the public have arose to the point when the Korean Medical Association established a medical terms enactment in 1976 and made the first series of medical terms. These efforts have been continued to the second in 1983, the third in 1992 and the fourth series in 2001. Throughout this revision, we wish new terms of fourth series may contribute to the better communication between the doctors and patients. It will be able to function as a better and enhanced tool to the public who require medical information. The terms of present lecture are based on the fourth series of medical terms. Because it is irrational to use all the reformed terms, in this lecture we have used the most commonly used clinical terms as a hope for the pediatricians to give better medical treatment.