Pediatric drug research is still substandard, not reaching the same quality level as adult drug research. Despite the efforts made by the Food and Drug Administration and European Medicines Agency to reduce off-label use in children, the lack of clinical studies involving the pediatric population still stands. Pharmacokinetic and pharmacodynamics studies (PK/PD) taking growth and maturation into account are necessary to rationalize dosing strategies in children. Currently, traditional animal models such as rats, mice, dogs and primates are used to conduct pharmacokinetic and pharmacodynamic studies, however age-related trials are rather uncommon. Moreover, these species have several shortcomings as animal models, such as a different physiology and anatomy of the gastrointestinal tract in dogs or the ethical aspects for the use of primates. In contrast, piglets might be potential biomedical pediatric animal models because of the good resemblance with humans, anatomically, physiologically and biochemically. This review summarizes the comparative anatomy and physiology and postnatal development of piglets and infants, focusing on six major topics, namely growth, cardiovascular system, gastrointestinal tract, liver, kidney and integument. Furthermore, the application of piglets as animal model in pediatric PK/PD research is discussed.