This article aimed to assess posttraumatic growth among participating and nonparticipating families of organ donors in grief support groups. The program, in the form of both face-to-face and WhatsApp groups, is unique in that it extends over many years without limitation for a predefined period, is open to both immediate and extended family members, and is conducted according to predetermined topics. A questionnaire was completed by 84 participants and 115 non-participant family members. Most participants had attended for between 1 and 5 years (57.2%), although 33.3% had participated for >5 years, including 16.7% who participated for >10 years. All measures of posttraumatic growth were significantly higher in group participants (3.40 [0.75] vs. 3.15 [0.75], p = .010) than non-participants. The often-prolonged participation in the groups suggests there may be an important need for ongoing contact with and support for these families even many years after the loss.