Pain in children, especially in infancy, is frequently underestimated. Surprisingly, in ancient times, writers were more aware of the existence of pain in infancy and the need for its relief than in 20th century. They rated pain perception as being higher in infancy than in childhood. The study by McGraw (1941), although badly designed, convinced the vast majority of clinicians that infants do not feel pain and do not require analgesia. This theory, reinforced by the fear of using opioids in young children, dominated medical thinking for more than 30 years. Later studies on pain perception in foetuses, and careful analysis of infants' reactions to blood sampling, helped doctors to understand the necessity of adequate analgesia in young children. In this review, we present the approach to pain in children over centuries, from ancient times to the latest developments in this field.