Objective: Given the lack of maintenance interventions for eating disorders, a program delivered via the short message service (SMS) and text messaging was developed to support patients after their discharge from inpatient treatment. Method: The efficacy of the intervention was studied in a randomized controlled trial. Additionally, its impact on the utilization of outpatient treatment during follow-up was investigated. One hundred sixty-five female patients with bulimia nervosa or a related eating disorder not otherwise specified were randomly assigned to a control group (treatment as usual; TAU) or an intervention group (SMS-based maintenance intervention; SMS). After hospital discharge, participants in the intervention group submitted a weekly symptom report via text message for 16 weeks and received tailored feedback. Primary outcome was the rate of partial remission 8 months after discharge from inpatient treatment. Results: The difference in remission rates reached significance in the intent-to-treat analyses (SMS = 51.2%; TAU = 36.1%), X[superscript 2](1) = 3.81, p = 0.05, and approached significance in the completer analysis (SMS = 59.2%; TAU = 43.5%), X[superscript 2](1) = 3.44, p = 0.06. There were no differences in the utilization of outpatient treatment. Remission rates between the intervention and control groups were not significantly different among patients who used outpatient treatment (63.2% vs. 55.6%), X[superscript 2](1) = 0.44, p = 0.51. A significant difference was found in those who did not utilize such treatment (54.5% vs. 30.3%), X[superscript 2](1) = 3.97, p = 0.046. Conclusion: The aftercare intervention was efficacious in enhancing treatment outcome after discharge from inpatient treatment. (Contains 3 figures and 2 tables.)