Abstract: Human peripheral blood mononuclear cells (PBMC) were separated from blood by ficoll-hypaque density gradient centrifugation and rhesus monkey spleen cells were isolated from fresh spleens. To isolate inner cell masses (ICMs) by immunosurgery from human or rhesus monkey embryos and establish embryonic stem cell (ES cell) lines, antiserums were prepared by injecting rabbits with human PBMC or rhesus monkey spleen cells, with 4×10⁸ cells every time, once a week and three times in all, respectively. Our results were listed as below: 1) Rabbit anti-human PBMC antiserum has a titer around 1∶320 and rabbit anti-rhesus spleen cell antiserum has a titer around 1∶640; 2) The trophectoderm were lysed by immunosurgery using the rabbit anti-human PBMC or anti-rhesus spleen cell antiserum followed by exposure to guinea pig complement. ICMs were successfully isolated from 15 human blastocysts and 33 monkey blastocysts. These results indicated that our antiserums could be used for collecting human or monkey ICM cells and they would play important roles in isolating new human or rhesus monkey ES cells in the future.