Objective: Multiple myeloma (MM) cells have been shown to be insensitive to NK-92-mediated killing.The adoptive immunotherapy with NK cells reprogramming with a chimeric antigen receptor (CAR) proved to be a promising therapeutic strategy in several malignancies.Methods: Genetically modified NK-92MI cells carrying a CAR that consists of an anti-CD138 single-chain variable fragment (scFv) were generated using a flexible hinge region connected to the CD3ξ chain as a signaling moiety to enhance NK cell reactivity and recognition specificity toward CD138-positive MM cells.The cytotoxicities of the retargeted NK92MI-scFv toward CD138 positive MM cell lines and primary MM cells were detected using LDH release assay and AnnexinⅤ-PI apoptotic analysis via FACS.The secretions of IFN-γ and granzyme B and the expressions of CD107a and Fas-ligand by NK-92MI-scFv in response to CD 138-positive target cells were determined using ELISA assay or flow cytometric analysis.The in vivo anti-MM activity of NK-92MI-scFv was investigated in xenograft mice models.