To study the functions of decidual CD56+ NK-like cells in the mater CD56+NK-like cells were seperated by trypsin degradation and fractionation on Percoll gradient. Improved lactic dehydergenase (LDH) releasing test was used to assay the cytotoxicity of decidual NK cells and peripheral blood lymphocytes (PBLs). It was found that decidual CD56+ NK-like cells showed lower cytotoxicity activity than PBLs. In conclusion,during normal pregnancy,the decidual CD56+ NK-like cells might be inhibited to permit the inv...