Empirical evidence on the longer-term effectiveness of evidence-based treatments for adolescents with post-traumatic stress disorder (PTSD) in low-resource settings is needed. The aim of the study was to evaluate the maintenance of treatment gains achieved in a comparative study of effectiveness of prolonged exposure therapy for adolescents (PE-A) and supportive counselling (SC) in adolescents with PTSD up to 24-months post-treatment.

Sixty-three adolescents (13–18 years) with PTSD were randomly assigned to receive either of the interventions comprising 7–14 sessions of treatment provided by trained and supervised non-specialist health workers (NSHWs). The primary outcome measure was PTSD symptom severity, as independently assessed on the Child PTSD Symptom Scale, at pretreatment, post-treatment, and at 3-, 6-, 12- and 24-months post-treatment follow-up (FU) evaluations.

Participants in both the prolonged exposure and SC treatment groups attained a significant reduction in PTSD symptoms and maintained this reduction in PTSD symptoms at 12- and 24-month assessment. Participants receiving prolonged exposure experienced greater improvement on the PTSD symptom severity scale than those receiving SC at 12-months FU [difference in PE-A v. SC mean scores = 9.24, 95% CI (3.66–14.83), p < 0.001; g = 0.88] and at 24-months FU [difference in PE-A v. SC mean scores = 9.35, 95% CI (3.53–15.17), p = 0.002; g = 0.68].

Adolescents with PTSD continued to experience greater benefit from prolonged exposure treatment than SC provided by NSHWs in a community setting 12 and 24 months after completion of treatment.