The illness severity scoring systems provide objective measures for inter- and intra-unit comparisons with time and also provide useful information for comparing the severity of illness of patients, at the time of enrollment into clinical trials. These scores are an essential part of the improvement in clinical decisions and in stratifying patients with poor outcomes. Appropriate application of these models helps in decision-making at the right time and in decreasing mortality. However, it is also important to note that the choice of illness scores should accurately match the setting in which they are designed. In Indian setting, there is no Pediatric Intensive Care Unit illness severity score is designed until now as per our patient profile and resources. The purpose of this review article is to provide an idea regarding the evolution of illness severity scores in developed countries till date along with their utility. This review emphasizes the need for the development of pediatric illness severity score as per the local resources.