The accumulation of basic researches and clinical studies related to cytokine-induced killer (CIK) cells has confirmed their safety and feasibility in treating malignant diseases. This review summarizes the available published literature related to the biological characteristics and clinical applications of CIK cells in recent years. A number of clinical trials with CIK cells have been implemented during the progressive phases of cancer, presenting potential widespread applications of CIK cells for the future. Furthermore, this review briefly compares clinical applications of CIK cells with those of other adoptive immunotherapeutic cells. However, at present, there are no uniform criteria or large-scale preparations of CIK cells. The overall clinical response is difficult to evaluate because of the use of autologous CIK cells. Based on these observations, several suggestions regarding uniform criteria and universal sources for CIK cell preparations and the use of CIK cells either combined with chemotherapy or alone as a primary strategy are briefly proposed in this review. Large-scale, controlled, grouped, and multi-center clinical trials on CIK cell-based immunotherapy should be conducted under strict supervision. These interventions might help to improve future clinical applications and increase the clinical curative effects of CIK cells for a broad range of malignancies in the future.