To establish the criteria of oocyte selection and optimize the success rate of in vitro embryo production (IVEP) in water buffaloes, a series of experiments were conducted. Cumulus-oocytes complexes (COCs) were classified and grouped to examine the following: morphology of the oocytes (rank A, with 5 layers of dense cumulus mass, rank B, with 2<5 layers, rank C, with <2 layers, rank D, oocytes denuded from cumulus cells, and rank E, oocytes with swelled and expanded cumulus mass); granulation of the ooplasm (homogeneous if ooplasm is evenly granulated and heterogeneous if ooplasm is uneven); compactness of cumulus cells (compact when the surrounding cumulus mass are tightly connected, and loose when the cumulus mass are slightly expanded); size of the ooplasm (<100, 100<119, 12-139, >140 μm). Meiotic competence and embryo development after in vitro fertilization were assessed. Results showed that rank A COCs with homogeneous ooplasm, compact cumulus cells, and >120 μm ooplasm had the highest meiotic and developmental competence with optimum development when fertilized at 24-26 h of in vitro maturation. COCs with heterogeneous ooplasm and loose cumulus cells were developmentally competent but required shorter duration (20-22 h) of in vitro maturation. Ranks C, D and E oocytes had high degeneration rate. Oocytes with ooplasm <100 μm had poor developmental competence and most failed to cleave after in vitro fertilization.