The prevalence of morbid obesity is increasing, with a corresponding increase in the demand for bariatric surgery, a proven effective treatment option. Bariatric surgery has potentially severe complications, including micro- and macronutrient deficiencies. Additionally, stenosis and ulceration of the anastomosis, reflux oesophagitis, cholelithiasis, steatohepatitis and altered pharmacokinetics and -dynamics may occur. Doctors in both the hospital setting and general practice will be increasingly confronted with the occasionally adverse long-term effects of bariatric surgery. Early detection, efficient follow-up and a multidisciplinary team approach are crucial in preventing and adequately treating the complications of bariatric surgery.