The objective of this study was to compare the effects of containment and swaddling on premature infants ' heart rates (HR), oxygen saturation (SpO(2), and the Premature Infant Pain Profile (PIPP) scores after heelstick. The study used a cross-over experimental design, 32 premature infants with gestational age < 37 weeks, bodyweight <or= 2500 grams, and no diagnosis of congenital heart disease, deformity, sepsis or <or=Grade 3 intraventricular hemorrhage were selected as subjects. Each subject was randomly assigned to containment or swaddling once while undergoing two heelsticks in different time periods. Heart rate, oxygen saturation, facial expression and PIPP score were recorded from 5 minutes before to 11 minutes after heelstick. According to the paired t test, the results showed (1). that mean HR was higher and mean SpO(2) was lower than their respective baseline values under the two interventions after heelstick (p <.05), and that premature infants in swaddling returned to their baseline HR and SpO(2) values in shorter time periods compared to those in containment, though the variations of HR and SpO(2) between the two interventions exhibited no significant differences; and (2). that pain responses to heelstick under swaddling yielded lower scores than those under containment according to the total PIPP scores, but significant difference between the two interventions was only found at the 3rd and 7th minute. As a whole, there is little difference between the effects of swaddling and containment on attenuating physiological and behavioral stress caused by acute pain. The results of this study can serve as an evidence basis for nursing interventions in acute pain for premature infants. In clinical practice, containment and swaddling can be administered interchangeably according to patients' individual differences.