BACKGROUND The aim of this study was to evaluate the feasibility, safety, and diagnostic accuracy of endorectal ultrasound-guided aspiration and drainage of pelvic fluid collections. METHODS All patients who underwent endorectal ultrasound-guided aspiration and/or drainage of pelvic fluid collections were included in this prospective study. Patients were prepared using bowel lavage and a single-dose antibiotic combination. The procedure was carried out in the lithotomy position usually without sedation. All aspirates were examined microbiologically and/or cytologically. RESULTS Twenty-nine patients [18 females and 11 males; median age, 67 years (range, 18-79)] underwent 33 endosonographic controlled aspirations. No procedure-related complications were encountered. In 22 cases (76%) the lesions were encountered following a surgical procedure. Fluid amounts varied between 5 and 750 ml. Fluids were sterile in 14 cases (42%). These fluid collections were hematomas, seromas, peritoneal cysts, and a mucocele. Microorganisms were found in the remaining 19 aspirations (58%), i.e., abscesses (n = 16) and infected hematomas (n = 3). A transrectal (n = 14) or transvaginal (n = 2) drainage catheter was placed in 16 patients under endosonographic guidance. Only two patients required a subsequent laparotomy for definitive treatment of their septic focus, whereas all other patients could be treated successfully by this conservative approach. CONCLUSIONS Endoscopic ultrasound-guided transrectal aspiration and drainage of pelvic fluid collections is a safe method with a favorable outcome because it avoids unnecessary operations in selected patients.