Summary Background Angiodysplasia (AD) of the gastrointestinal (GI) tract is an important condition that can cause significant morbidity and –rarely – mortality. Aim To provide an up‐to‐date comprehensive summary of the literature evaluating this disease entity with a particular focus on pathogenesis as well as current and emerging diagnostic and therapeutic modalities. Recommendations for treatment will be made on the basis of the current available evidence and consensus opinion of the authors. Methods A systematic literature search was performed. The search strategy used the keywords ‘angiodysplasia’ or ‘arteriovenous malformation’ or ‘angioectasia’ or ‘vascular ectasia’ or ‘vascular lesions’ or ‘vascular abnormalities’ or ‘vascular malformations’ in the title or abstract. Results Most AD lesions (54–81.9%) are detected in the caecum and ascending colon. They may develop secondary to chronic low‐grade intermittent obstruction of submucosal veins coupled with increased vascular endothelial growth factor‐dependent proliferation. Endotherapy with argon plasma coagulation resolves bleeding in 85% of patients with colonic AD. In patients who fail (or are not suitable for) other interventions, treatment with thalidomide or octreotide can lead to a clinically meaningful response in 71.4% and 77% of patients respectively. Conclusions Angiodysplasia is a rare, but important, cause of both overt and occult GI bleeding especially in the older patients. Advances in endoscopic imaging and therapeutic techniques have led to improved outcomes in these patients. The choice of treatment should be decided on a patient‐by‐patient basis. Further research is required to better understand the pathogenesis and identify potential therapeutic targets.