Recently, chimeric antigen receptors (CAR) T cell therapies have been developed rapidly as a promising treatment for malignancies. The expectations are based on the predefined specificity of CAR T cells by an antibody-derived binding domain that acts independently of the natural T cell receptor, recognizes targets independently of presentation by the major histocompatibility complex and allows targeting toward virtually any cell surface antigen. To date, CD19-specific CAR T cells have exhibited dramatic clinical responses that are accompanied by significant toxicity in hematological malignancies. In this paper, we will review the current status, safety, and toxicity of chimeric antigen receptors in hematology. (Am J Transl Med 2017. 1:195-211).