Purpose: The aim of this study was to describe how contextual factors related to the clinical setting of a pediatric HSCT unit influenced children's communication of pain to their health-care providers and parents during hospitalization. Design and methods: A qualitative case study design was conducted in two-phases in a tertiary level pediatric HSCT unit. The Social Communication Model of Pain provided the conceptual framework for the study. In phase one participants were parents and phase two participants were health-care providers and children in a pediatric HSCT unit. Parents participated in semi-structured interviews at 30- and 90-days post-transplantation regarding their child's communication of pain. Naturalistic observations of children receiving clinical care were conducted and health-care providers participated in semi-structured interviews. Results: Children extensively denied pain to their parents and health-care providers. When children did communicate pain, they were motivated by a need to seek interventions for their pain. Children's willingness to communicate pain was influenced by the physiological impact of HSCT therapy, their previous experiences of pain, their relationship with parents and health-care providers and parents and an environment of fear and uncertainty. Conclusions: There is a pressing need for child-centric approaches to support children to communicate their pain experiences to overcome the limitations imposed by the complexity of their medical treatment and the clinical environment in which they receive healthcare. Practice implications: In the context of HSCT therapy children may not communicate pain until pain is severe, and no longer bearable, or outright deny the presence of pain.