The multifetal reduction (MFR) procedure is usually reserved for high-order multiple pregnancies, and aspirated tissues are typically discarded. In this study, cells obtained from MFR tissue (termed multifetal reduction embryonic cells (MFR-ECs)), were characterized in vitro by genotypic and phenotypic analyses and tested in vivo by injection under the kidney capsule of nude mice. MFR-ECs were highly proliferative in culture and showed a normal karyotype by microarray CGH. Immunohistochemical analysis at day zero showed positive focal staining for desmin, S-100 protein, synaptophysin and chromogranin. Histology examination showed a mixture of cells from the three germ layers at different stages of differentiation. Markers of these stages included important developmental transcription factors, such as beta three-tubulin (ectoderm), paired box 6 (ectoderm) and alpha-smooth muscle actin (mesoderm). Quantitative polymerase chain reaction (qPCR) showed down-regulation of the mRNAs of cancer-related genes such as TP53. In vivo transplantation in nude mice showed a typical hyaline cartilage plate and no teratoma formation. Thus, MFR-ECs represent a rich, unique source for studying stem cell development, embryogenesis and cell differentiation.