This study aimed to analyze the parameters used by the nursing staff of a public hospital in Bahia for pain assessment in premature newborns and to describe the interventions used to relieve the pain. This is a qualitative descriptive study that was carried out through semi-structured interviews with ten participants, in the period from December 2008 to January 2009. The data were analyzed through content analysis. The results showed the use of crying and facial expression as the clinical indications of pain premature newborns and that the interviewed participants use, on a non-systematic basis, non-pharmacological measures in order to ease this process. We suggest the introduction of pain as the fifth vital sign to be evaluated and the use of scales, contributing to excellence and humane care.