Introduction  Small bowel neoplasms are rare entities, with only 3.2% of gastrointestinal tumors localized in this segment. Adenocarcinoma is the second most common histologic type among small bowel neoplasms. The disease's symptoms are non-specific, with abdominal pain being the most common. Among the complications, fistulas are a far rare condition. Case report  We present the case of an 86-year-old woman, hypertensive, diabetic, and former smoker, with lower abdominal pain, hematuria, fecaluria and fever associated with weight loss. Upon physical examination presented pale mucous membranes. Magnetic resonance imaging of the abdomen showed parietal thickening in the distal ileum segment with an anterior wall bladder fistula. Absence of metastases. Subjected to transurethral endoscopic biopsy of the bladder lesion, which anatomopathological study was compatible with invasive mucinous adenocarcinoma. An enterectomy was performed with primary enteroanastomosis, associated with partial cystectomy by videolaparoscopy. Anatomopathological study of the surgical specimens concluded mucinous adenocarcinoma with signet ring cells located in the small bowel and bladder. Immunohistochemical exam has identified findings compatible with mucinous adenocarcinoma of origin in the small bowel. The patient evolved well, being discharged, and returned to postoperative follow-up without signs of relapse of the disease. Conclusion  The relative inaccessibility of the small bowel and the malignant neoplasms’ non-specific symptoms make an early diagnosis difficult. Discovery of the disease, often only at an advanced stage, results in complications and less effective therapy. The laparoscopic approach might be advantageous and effective in the treatment of advanced small bowel cancer with invasion of adjacent structures.