The purpose of this study was to describe the experience of pain in infants and children in response to venipuncture and intravenous cannulation. Data on physiological, behavioral, and subjective responses were collected from 90 infants and children, in subgroups of 1 to 12 months, 1 to 3 years, 4 to 6 years, and 7 to 12 years. Changes in behavior were significant in all four groups, although the toddler group was the only group that showed a significant physiological change. The subjective measures showed that the children were able to identify their pain sites and intensity.