Polyimides are a class of well-known high-performance polymers combined the excellent mechanical, electrical, and thermal properties and widely applied in many high-tech fields. Traditional polyimides can only be processed in the state of soluble intermediates with a hazardous step of cyclodehydration and elimination of a nonvolatile polar solvent. Therefore, a great effort has been devoted to the development of soluble polyimides that can be processed in the full imidation state. The incorporation of side groups into the polyimide backbone is an efficient approach to resolve above problems with a little sacrifice of its inherent merits. The subtle variation of side groups in polyimide backbones has allowed researchers to tune their final properties. In particular, some special side groups can endow polyimides the specific property or functionality to broaden their application fields. In this article, we summarize the synthesis of polyimides with side groups in recent 20 years and further discuss the effect of side groups on their physical and specific properties. The future research directions of polyimides with side groups are also discussed. (C) 2016 Wiley Periodicals, Inc.