Painful procedures may lead to both long- and short-term complications in low birth weight (LBW) infants. This study investigated neonatal pain responses (grimace, slight cry expression, increased cry expression, and knee/leg flexion) during six painful and three nonpainful procedures. The 30 LBW infants studied were less than 48 hours of age and less than 34 weeks gestation, with a mean birth weight of 1,320 gm. The design was comparative; data analysis included repeated measures of analysis of variance, independent t-tests, and paired t-tests. The four pain responses were found to be present 75 to 100 percent of the time after painful procedures (suctioning, skin puncture, dressing change or removal, discontinuation of intravenous line, and insertion of a nasogastric tube). They were also found to be present 49 to 69 percent of the time after nonpainful procedures (total position change, addition/withdrawal of fluid from umbilical catheter, and IV administration of medication).