Magnetic resonance imaging is widely used as a diagnostic tool in the clinic. Magnetic resonance imaging contrast agents such as gadolinium are very often used to improve the quality of images acquired by magnetic resonance imaging. Until recently, it was believed that gadolinium is effectively cleared within 24 hours after intravenous injection, and that it does not have any harmful effects on the human body. However, recent studies on animals and analyses of clinical data have indicated that gadolinium is retained in the body for many years post-administration, and may cause various diseases. This is especially concerning for paediatric patients because of the anticipated longer time of exposure and its effects on children’s continuing development, and patients who receive repeated magnetic resonance imaging scans and hence repeated doses of gadolinium. Here, we give a short review of the most recent findings on the accumulation and side effects of gadolinium.