Abstract Zhao, J., Hattori, M.-A. and Fujihara, N. 1998. Effect of Japanese Kampo Medicines on in vitro maturation of bovine oocytes and developmental capacity of embryos. J. Appl. Anim. Res., 13: 93–104. Experiments were conducted to examine the effect on in vitro maturation of bovine oocytes and subsequent developmental capacity of embryos of several Japanese Kampo Medicines (JKMs), which have been reported to be effective in the treatment for reproductive failure in both women and rats. In the first experiment, the most effective JKM and its optimal concentration were determined by adding JKMs to bovine calf serum (CS)-free TCM 199 medium and examining developmental capacities of oocytes after fertilization in vitro. Similarly, in the second experiment, the comparison of the effect of the most effective JKM on in vitro maturation with that of CS was carried out. The morphological characteristics of oocytes after in vitro maturation were also examined using transmission electron microscopy. Keishibukury...