Patients are often referred for evaluation of a wide range of GI complaints including dysphagia, abdominal pain, bloating, nausea, constipation or diarrhoea. Many are diagnosed with 'functional' disease when endoscopy or conventional radiological studies fail to identify an anatomic cause for the patient's symptoms. In such cases nuclear medicine offers non-invasive methods for objectively demonstrating disease involving different areas of the gastrointestinal tract. Increasingly scintigraphy is playing a primary role in the evaluation of patients with suspected acute cholecystitis, active gastrointestinal bleeding, gastroparesis, and small and large bowel motility disorders. In addition, it supplements other studies when results are inconclusive in diagnosing oesophageal dysmotility, gastro-oesophageal reflux, acalculous cholecystitis, and postoperative complications of gastrointestinal surgery.