Background <p>The primary indication for ERAT is acute uncomplicated appendicitis; however, in recent years, the successful treatment of appendiceal abscesses in adults has been reported in several cases. Further investigations are warranted to establish the feasibility of ERAT for the management of appendiceal abscesses.</p> Aims <p>This study aimed to evaluate the efficacy and safety of endoscopic retrograde appendicitis therapy (ERAT) for the treatment of acute periappendiceal abscess in adults.</p> Methods <p>This retrospective study included 30 adult patients with acute periappendiceal abscess who underwent ERAT at the Digestive Center of Suining Central Hospital between July 2021 and March 2025. The success rate (technical and clinical), procedure time, intervention time, visual analog scale (VAS) score, length of hospital stay, complications, and absorption condition of the abscesses 3&#xa0;months after the procedure were recorded and analyzed.</p> Results <p>The technical success rate of ERAT was 80%, and the clinical success rate was 83.3%. The median procedure time was 14.5 (interquartile range [IQR], 11.8–16.5) minutes. The median ERAT intervention duration was 7.0 (IQR, 4.8–10.0) days. The postoperative VAS score was significantly decreased (<i>P</i> &lt; 0.001), and the average length of hospital stay was 6.7 ± 2.4&#xa0;days. Three months after the procedure, the abscesses were completely absorbed in 87.0% of the patients and partially absorbed in 13.0% of the patients. Two patients developed postoperative complications, namely, abscess dissemination and transient high fever.</p> Conclusion <p>In adult patients with acute periappendiceal abscess, ERAT may be an alternative and effective treatment option in the early stage.</p>