ObjectiveTo systematically evaluate 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 cell counts, with a treatment interval of 14-21 days and a frequency of 3-6 injections. The overall response rate for NK cell therapy was 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 malignant tumors, and some studies have shown that NK cell therapy has a relieving effect. However, due to limitations in the number and quality of studies included, the above conclusions come from a qualitative synthesis of individual studies and need to be validated by more high-quality studies.