Human embryonic stem cells (HESCs) are defined as self-renewing cells that retain their ability to differentiate into all cell types of the body. They have enormous potential in medical applications and as a model for early human development. There is a need for derivation of new HESC lines to meet emerging requirements for their use in cell replacement therapies, disease modeling, and basic research. Here, we describe a modified culture medium containing human recombinant leukemia inhibitory factor and human basic fibroblast growth factor that significantly increases the number of human blastocysts formed and their quality, as well as the efficiency of HESC derivation from poor-quality embryos. Culturing poor-quality embryos in modified medium resulted in a two-fold increase in the blastocyst formation rate and a seven-fold increase over the derivation efficiency in conventional medium. We derived 15 HESC lines from poor-quality embryos cultured in modified culture medium and two HESC lines from quality embryos cultured in conventional culture medium. All cell lines shared typical human pluripotent stem cell features including similar morphology, normal karyotypes, expression of alkaline phosphatase, pluripotency genes, such as Oct4, and cell surface markers (SSEA-4, TRA-1-60, TRA-1-81), the ability to form teratomas in SCID mice, and the ability to differentiate into cells of three embryonic germ layers in vitro. Our data suggest that poor-quality embryos that have reached the blastocyst stage in our modified culture medium are a robust source for normal HESC line derivation.