Morbid obesity is a growing problem worldwide and has subsequently resulted in a wide application of bariatric surgery to achieve long-term weight loss and improvement of obesity-related co-morbidities. In spite of these clinical benefits, vitamin deficiencies are common after bariatric surgery; therefore, lifelong multivitamin supplementation (MVS) is recommended. However, patient adherence to MVS intake is generally poor. The aim of this narrative review is to analyse which factors influence the adherence of MVS intake after bariatric surgery. To provide an extensive overview, we will discuss the different factors that influence MVS use in patients who underwent bariatric surgery, but also review the literature on MVS in other patient groups.