Purpose: To report a gastrointestinal stromal tumour (GIST) presenting with melena in a dual-antiplatelet-treated patient and to highlight challenges in diagnosis and organ-preserving surgical management. Methods: We describe a 54-year-old male with coronary artery disease on antiplatelet therapy who presented with melena and severe anaemia. The diagnostic workup included upper GI endoscopy and a contrast-enhanced CT scan, followed by a sleeve gastrectomy. Histopathology, immunohistochemistry, and risk stratification guided adjuvant therapy. Results: Endoscopy demonstrated a submucosal ulcerated bulge in the posterior gastric wall. CT revealed a 4.5 × 3.8 cm mass adherent to the pancreatic head/body. Sleeve gastrectomy resulted in an R0 resection; the postoperative course was uneventful. Histopathology confirmed spindle cell GIST (<5 mitoses/50 HPF) with CD117 and CD34 positivity. Classified as intermediate-risk, adjuvant imatinib (400 mg/day) was initiated. At 6-month follow-up, no recurrence was detected. Conclusion: In patients with melena on antiplatelet therapy, GIST should be suspected. Dense pancreatic adherence does not necessarily imply invasion; organ-sparing resection is feasible, followed by tailored adjuvant therapy.