Abstract The Internet-based psychotherapeutic intervention Onco-STEP for adolescent and young adult (AYA)-aged survivors of pediatric cancer was developed, implemented, and participants' satisfaction was evaluated by use of questionnaires. The intervention consisted of two modules: "Looking Back," aimed to reduce posttraumatic stress symptoms, and "Looking Ahead," supported coping with cancer-related fears of relapse and progression. The writing program was fully completed by 20 participants (Mage=27.3±4.8 years at study; 70% female). The majority was satisfied and perceived the treatment components as helpful. Results demonstrate that an Internet-based psychotherapeutic intervention for AYA-aged survivors of pediatric cancer is feasible and accepted by the target population.