ObjectiveTo examine sustainability of symptom outcomes of a 1‐year phase‐based trauma‐focused, multimodal, and multicomponent group therapy in a day treatment program for posttraumatic stress disorder (PTSD) over an average period of 7 years. Method Iranian and Afghan patients (N = 69) were assessed with self‐rated symptom checklists for PTSD, anxiety, and depression symptoms before (T1), after (T2), and up to 11 years upon completion of the treatment (T3). A series of mixed model regression analyses was applied to determine the course of the measured symptoms over time. Results At T2, all symptoms were reduced, but PTSD symptoms showed the strongest reduction. The trend of symptom reduction continued up to 5 years posttreatment and was similar for all the examined symptoms. After 5 years, all symptoms started to worsen, but remained under baseline levels at T3. Conclusions The applied treatment appears to improve mental health of the studied sample on both the short and longer term.