This study was conducted to evaluate the effects of supplementation of human or murine leukemia inhibitory factor (hLIF or mLIF) to synthetic oviduct fluid medium (SOFM) containing BSA and to determine their effective dosage on in vitro development of bovine morulae cultured singly or in a group. Morulae were produced by culture of in vitro matured (IVM), fertilized (IVF) and cleaved (2- to 4-cell) embryos in SOFM+BSA for 124 h after IVF, and then cultured singly (1 embryo/30 μl drop) or in a group (4-5 embryos/30 μl drop) in SOFM+BSA supplemented with 0 (control), 500, 1,000, 2,000, 4,000 and 6,000 U/ml of each hLIF or mLIF at 39℃ in an atmosphere of 5% CO₂, 7% O₂, 88% N₂ and >95% humidity. Culture of embryos in a group improved (p<0.01) embryo development to hatched blastocysts compared to a single culture. Both hLIF and mLIF significantly (p<0.05) increased development to hatched blastocysts when morulae were cultured singly, but not when cultured in a group. The most effective dosage of mLIF was 1,000 U/ml (p<0.05), but there was no significant difference in the addition of hLIF with different doses (500 to 6,000 U/ml) tested. This results indicate that a group culture may be more effective on embryo development than a single culture and supplementation of hLIF or mLIF to SOFM+BSA improve in vitro development into hatched blastocysts of bovine morulae derived from in vitro maturation and fertilization when cultured singly.