The aim of this study was to evaluate the effects of phosphate, aimno acid, and BSA on in vitro development of mammalian embryos. In vitro-matured and -fertilized(IVM/IVF) bovine embryos were cultured in simple, chemically defined, protein-free medium(mTLP-PVA0. When the phosphate concentration of mTLP-PVA supplemented with 19 amino acid were adjusted to 0.0, 0.10, 0.35, 1.05 and 2.10mM by the concentration of sodium phoshpate, there were no significant different in development ability of IVM/IVF bovine embryos cultured in the medium containing from 0.00 to 1.05mM phosphate until 48 hours post-insemination, However, proportion of embryos developing to $$8-cell and morula at 96 and 144 hours post- insemination, respectively, was significantly increased in the medium with o.35 mM phosphate(p<0.05). There was significant difference between O.10(18%)-0.35(24%)mM phosphate and 1.05(13%)-2.10(1%)mM phosphate in supporting development to blastocyst(p<0.05). When IVM/IVF bovine embryos were cultured in the medium supplemented with 19 amino acids, significant different was observed in the proporton of embryos reaching $$8-cell(49-50%), morula(38-40%) and blastocyst (29-32%) stages at 96, 144, and 192 hours post-insemination, respectively(p<0.05). Glutamine alone had no benefit on embryo development. When BSA was added to mTLP-PVA with 0.35mM phosphate, glutamine and 19 amino acids at 8, 48, 120 hours post-insemination, BSA significantly enhanced the development ability ofb embryos reaching $$2-cell (74-77%), $$8-cell (49-53%), morula(43-47%), and blastocyst(38-42%) stages at 48, 96, 144, and 192 hours post-insemination, respectively, regardless of the time of BSA addition.