Rare neuroendocrine tumours (NETs) that most commonly arise in the gastrointestinal tract can lead to carcinoid syndrome and carcinoid heart disease. Patients with carcinoid syndrome present with vasomotor changes, hypermotility of the gastrointestinal system, hypotension and bronchospasm. Medical therapy for carcinoid syndrome, typically with somatostatin analogues, can help control symptoms, inhibit tumour progression and prolong survival. Carcinoid heart disease occurs in more than 50% of these patients and is the initial presentation of carcinoid syndrome in up to 20% of patients. Carcinoid heart disease has characteristic findings of plaque-like deposits composed of smooth muscle cells, myofibroblasts, extracellular matrix and an overlying endothelial layer which can lead to valve dysfunction. Valvular dysfunction can lead to oedema, ascites and right-sided heart failure. Medical therapy of carcinoid heart disease is limited to symptom control and palliation. Valve surgery for carcinoid heart disease should be considered for symptomatic patients with controlled metastatic carcinoid syndrome. A multidisciplinary approach is needed to guide optimal management.