Background <p>Complex anal fistulas remain a therapeutic challenge due to high recurrence rates and the risk of incontinence associated with conventional treatments. Microfragmented autologous adipose tissue has emerged as a sphincter-sparing option with potential regenerative and anti-inflammatory properties. This study aimed to evaluate the safety and efficacy of its injection into the fistula tract combined with closure of the internal opening.</p> Methods <p>A single-center, retrospective, observational study was conducted between June 2019 and May 2025. All patients with complex anal fistulas treated with microfragmented adipose tissue processed with LIPOGEMS® system were included. Demographic data, fistula characteristics, surgical history, perioperative variables, postoperative morbidity, healing rate, and hospital stay were analyzed. Follow-up visits were performed weekly in the first month, and at 3, 6 and 12 months thereafter.</p> Results <p>A total of 28 patients with complex fistula were included. Mean patient age was 51.2 years (SD: 15.3), with predominance of males (69.7%). Most fistulas were medium or high transsphincteric (85.7%) and the main location was posterior (57.1%). 75% of patients had undergone previous curative-intent procedures. Median operative time was 71 minutes, and median processed adipose volume was 14 ml. Two postoperative complications were recorded (one abdominal hematoma-CD I and one perianal abscess-CD IIIa). After a median follow-up of 11.2 months, the overall healing rate was 46.4%, higher in primary (57.1%) and posterior fistulas (56.3%). Median hospital stay was one day, and median clinical closure occurred at 2.7 months.</p> Conclusions <p>LIPOGEMS® therapy appeared safe, feasible, and associated with encouraging healing outcomes, offering advantages in functional preservation and recovery. Larger prospective studies are needed to confirm these results and refine its role in fistula management.</p>