Chapter 34 provides an overview of the principles of colorectal surgery, and the common pathologies relevant to the speciality including colorectal cancer, inflammatory bowel disease, hernias, and perianal pathology. In addition, the acute abdomen, acute appendicitis, bowel obstruction, and acute diverticulitis are covered. Key investigations, operations, and procedures to see are summarized and include appendicectomy, colectomy, abdominoperineal resection, stoma, hernia repair, and the numerous investigations used in the context of an acute abdomen. Key knowledge and clinical skills relevant to colorectal surgery clinics are summarized with a particular emphasis on colorectal cancer, risk factors, symptoms/presentation, imaging studies, staging, and management. Inflammatory bowel disease may necessitate surgical intervention and the common acute and chronic presentations are summarized. The classification of abdominal wall hernias is outlined and key anatomical landmarks on clinical examination are illustrated. A list of differential diagnoses of groin lumps is presented with key investigations to differentiate them. Diverticular disease, haemorrhoids, anal fissures, rectal prolapse, and pilonidal disease are common and the clinical presentation, investigation, and management of each of these is outlined. Digital rectal examination is a key clinical skill in surgery and the steps involved are summarized. The anatomical approach to colorectal surgery is outlined and common approaches to the surgical management of appendicitis, hernia repair, hemicolectomy, primary anastomosis, and stoma surgery are presented. Mnemonics for recall of key anatomical landmarks are provided. Postoperative complications are outlined together with the approaches to management. An approach to assessment and management of the acute abdomen is outlined. Finally, key OSCE and examination topics relevant to colorectal surgery are outlined including stoma and hernia examination.