PURPOSE: In order to maintain the effect achieved in the psychosomatic rehabilitation measure, psychosomatic rehabilitation aftercare is indicated for most rehabilitation patients. Due to the low availability of aftercare therapists close to home, the use of digital offers is a possibility to enable access independent of location. The aim of the study was to evaluate the therapeutic effects of web-based aftercare in comparison to face-to-face (F2F) therapy (both on the conceptual basis of the Curriculum Hannover) in the equivalence study and to no standardized aftercare (care as usual, CAU) in the superiority study. METHODS: 300 rehabilitation patients with an indication for psychosomatic aftercare were assigned to the equivalence study if an aftercare service close to home was available and then randomized to F2F or online aftercare. Without a service close to home, the participants were assigned to the superiority study and randomized to online or CAU group. The outcomes (primary: psychological and somatoform complaints, secondary: subscales of the HEALTH-49, employment prognosis, ability to work) were assessed by online questionnaires at the end of rehabilitation, 9 or 12 and 15 or 18 months after rehabilitation and evaluated with multiple imputation and intention-to-treat-analyses. For the primary outcome, a sensitivity analysis was also carried out on the basis of the completed dataset. RESULTS: After excluding non-adherent participants, n=142 participants were evaluated in the equivalence study and n=111 in the superiority study. In the equivalence study, no significant differences (d=0,28 and 0,10 with ITT-analyses; d=0,09 and 0,03 with completed dataset) were found between online and F2F follow-up with regard to short-term and long-term psychological and somatoform complaints. In the superiority study, long-term psychological and somatoform complaints decrease in the online group, while in the CAU group they first decreased at T2 (d=0,56) and increased again at T3 (d=0,72). The latter finding is confirmed with the analysis of the completed dataset (d=0,12), while an increase was seen in the online group at T3 (d=0,10). CONCLUSION: According to the results of the present study, web-based psychosomatic aftercare seems to have a longer-term advantage for rehabilitants without access to previous aftercare. Compared to F2F implementation, it can be considered equivalent.