This chapter highlights a selection of the randomized clinical trials and meta-analyses related surgery. Across all specialities, clinical practice is increasingly relying on a robust evidence base to support patient management. Surgery is no exception to this trend. Wound infection rates are reduced when 4% chlorhexidine is used to prepare the skin preoperatively. Transverse incisions result in fewer incisional hernias and should be considered in acute and elective open surgery of the upper abdomen. Famotidine is effective in the prevention of gastric and duodenal ulcers and erosive esophagitis in patients taking low dose aspirin. The addition of 18F-FDG PET to the work up for surgical resection of colorectal liver metastases prevents unnecessary surgery in 1 in 6 patients. In carefully selected morbidly obese patients laparoscopic vertical-banded gastroplasty results in significantly more weight loss than laparoscopic adjustable silicone gastric banding. Laparoscopic surgery for rectal cancer has a similar complication rate to open surgery. It is associated with less blood loss and a shorter hospital stay without compromise of oncological outcome. Letrozole improves disease-free survival in postmenopausal women with endocrine-responsive early breast cancer. There is no advantage in using a switch protocol with tamoxifen.