ObjectiveTo systematically review the efficacy and safety of autologous natural killer cells (NK) cells for the treatment of malignant tumors. MethodsThe PubMed, Web of Science, and Embase databases were electronically searched to collect clinical studies on autologous NK cells for the treatment of malignant tumors from inception to July 1, 2023. Two reviewers independently screened literature, extracted data and assessed the risk of bias of the included studies. Descriptive analysis of the results were conducted. ResultsA total of 15 studies were included. The most common tumor type was non-small cell lung cancer. The dose of NK cell injections usually ranged from 7.0×107 to 7.0×109 cells, with a treatment interval of 14-21 days and a frequency of 3-6 injections. The overall response rate for NK cell therapy ranged from 0% to 77.78%. The main adverse effects were fever (3.98%), fatigue (1.99%), rash (0.4%), and dizziness (1.20%). ConclusionCurrent evidence shows that autologous NK cell therapy is safe for treating malignant tumors, and some studies have shown that NK cell therapy has a relieving effect. Due to the limited quality and quantity of the included studies, more high-quality studies are needed to verify above conclusion.