AimTo describe the variations of family members' conceptions of their supportive care needs (SCN) across the colorectal cancer (CRC) trajectory.DesignA descriptive qualitative study with a phenomenographic approach.MethodIndividual semi-structured interviews were conducted from May 2022 to October 2022 with 23 family members of persons diagnosed with colorectal cancer. The interviews were analysed using phenomenographic analysis following the Consolidated criteria for reporting qualitative research (COREQ) checklist.ResultsThe phenomenographic analysis resulted in five categories. Not of importance describes family members' needs as unimportant due to the good prognosis and the organization of care and in relation to the needs of others. Only satisfiable by professionals describes information possessed by the healthcare professionals as key, as well as the need for professional counselling for the family members to process their emotions. Managed by themselves describes family members preferring to manage their SCN themselves by turning to the appropriate social support and/or by using coping skills. Understood retrospectively describes SCN as only understandable when things have calmed down and as requiring one's own experience to understand. Left unmet describes SCN as unnoticed by the healthcare professionals or not brought to light by the family members, or family members not knowing where to turn for support.ConclusionSupportive care should involve individualized information, proactive and repeated assessments of needs across the trajectory, as well as encouragement of family members to reflect on their needs and to accept support when needed.ImpactThere is a gap in the literature regarding family members' SCN across the CRC trajectory which this study addresses. Findings show five categories of family members' conceptions of their SCN. Those findings could serve as a basis for the development of clinical colorectal supportive care across the cancer trajectory.Implications for the Profession and/or Patient CareFindings show that to offer family members of persons diagnosed with colorectal cancer support only at the time of diagnosis is insufficient. Instead, the healthcare team is recommended to proactively and repeatedly try to identify those in need and the characteristics of their needs. In addition, it is important to offer individualized information and strive to encourage family members to reflect on their situation and to not suppress their own needs if emerging.Reporting MethodReporting adheres to the consolidated criteria for reporting qualitative research (COREQ) checklist.Patient or Public ContributionNo patient or public contribution.