The objective of the study was to understand the criteria used by the nursing team to assess the pain of children hospitalized in a PICU. This is a qualitative study, targeting the Nursing team of a PICU at an inland hospital of the State of São Paulo. Focus groups were held alternating on odd and even days. The data was analyzed using Thematic Analysis proposed by Bardin. The analysis resulted in two categories, the first: "Experiencing the multidimensionality of children's pain: projections and feelings" and the second: "Pediatric pain assessment: care to be improved". Therefore, the interviewees understand the concept of pain in a specific way and do not use standardized criteria for pain assessment, which generates non-systematic assistance in the management of pain in hospitalized children.