Osteosarcoma (OS) is the most common primary malignant bone tumor, with an incidence worldwide of approximately one to three cases annually per million. It typically affects children and young adults with a second smaller peak of incidence in those individuals over the age of 50. The current main treatment is based on surgery and neoadjuvant chemotherapy leading to a long-term survival rate of 70%. However, these strategies are inefficient for the metastatic or relapsed osteosarcoma patients, in who the 5-year survival rate is less than 20%. In the last decades, alternative novel therapeutical approaches are being developed, including chimeric antigen receptors (CARs)-based immunotherapy, in which immune effector cells such as T-cells are genetically engineered to express CARs for improving the recognition and killing of tumor cells.  CAR-transduced T-cells (CAR-T-cells) have revolutionized the cancer therapy, however toxicities associated to this autologous therapy limit its widespread. Recently, among other immune cell types, natural killer (NK) cells have been proposed as a potential allogenic alternative due to their cytolytic capacity and their safety profile. Since NKG2D receptor (NKG2DR) is one of the most important activating receptor expressed in NK cells and osteosarcoma cells express ligands for NKG2DR, the aim of this study is the production of NKG2D-CAR-NK cells to target and kill more effectively osteosarcoma cells. The increased expression of NKG2DR on the surface of effector cells is correlated with an increased cytotoxic capacity. We hope that these results will stimulate the study of the potential of CAR-NK therapies against aggressive solid tumors.