Having a brother or sister who has a chronic illness (lasting >6 months and requiring long-term care) or life-limiting condition (LLC; where cure is highly unlikely and the child is expected to die) has major impacts on siblings. Parent–sibling illness-related communication may contribute to siblings’ capacity to cope.

In this study, we aimed to explore parent–sibling illness-related communication, from the perspectives of parents and siblings. We also aimed to qualitatively compare participants’ responses according to illness group (chronic illness vs. LLCs).

We collected qualitative data from siblings (32 with a brother/sister with a chronic illness, 37 with a brother/sister with an LLC) and parents of a child with a chronic illness (n = 86) or LLC (n = 38) using purpose-designed, open-ended survey questions regarding illness-related communication. We used an inductive qualitative content analysis and matrix coding to explore themes and compare across illness groups.

Two-thirds of siblings expressed satisfaction with their family’s illness-related communication. Siblings typically reported satisfaction with communication when it was open and age-appropriate, and reported dissatisfaction when information was withheld or they felt overwhelmed with more information than they could manage. Parents generally favored an open communication style with the siblings, though this was more common among parents of children with an LLC than chronic illness.

Our findings show that while many siblings shared that they felt satisfied with familial illness-related communication, parents should enquire with the siblings about their communication preferences in order to tailor illness-related information to the child’s maturity level, distress, and age.