Objectives: To explore the difficulties parents face when understanding their children’s reactions to parental cancer and parents’ reactions to their children’s perceived needs. Research approach: Qualitative interviews with cancer patients and their partners. Participants: Eleven patients and seven partners took part. Their children were aged 1-15 years. Eight patients were mothers and cancer was diagnosed median 28 (7-104) months ago. Methodological approach: Inductive analysis with systematic text condensation. Conclusions: Parents were groping in the dark when understanding their children’s reactions. They observed signs of distress in their children, but often avoided communication about emotional reactions. We suggest parental difficulties in containing own and children’s emotions as an important cause for this situation. Implications: Parents lacked relevant support offers for the family as a unit. Identification of children’s difficulties cannot be based on parental evaluation alone. We suggest family support as part of standard care for patients with minor children.