AbstractObjectiveThis study employs the concept of relational autonomy to understand how relational encounters with family members (FMs) and care providers may shape decisions around ovarian cancer patients’ clinical trial (CT) participation. The study also offers unique insights into howFMs view patients’ decision making.MethodsIn‐depth interviews were conducted with 33 patients with ovarian cancer who had been offered aCTand 39FMs. Data were inductively analysed using a thematic approach and deductively informed by constructs derived from the theory of relational autonomy (RA).ResultsPatients’ relationships, experiences and social status were significant resources that shaped their decisions. Patients did not give equal weight to all relationships and created boundaries around whom to include in decision making. Doctors’ recommendations and perceived enthusiasm were described as influential inCTdecisions. Both patients with ovarian cancer and theirFMs maintained that patients have the “final say,” indicating an individualistic autonomy. However, maintaining the “final say” in the decision‐making process is constitutive of patients’ relationships, emphasizing a relational approach to autonomy.FMs support patients’ autonomy and they do so particularly when they believe the patient is capable of making the right choices.ConclusionsAlthough ethical principles underlying informed consent forCTparticipation emphasize individual autonomy, greater attention to relational autonomy is warranted for a more comprehensive understanding ofCTdecision making.