A study was conducted to determine the effects to two dietary compounds, biochanin A and ferulic acid, on the reproductive performance of Japanese quail, Coturnix coturnix. These compounds may be present in the diet of wild birds during dry years or at the end of the growing season during normal years. Four treatment groups, each fed a diet supplemented with biochanin A or ferulic acid, and a control group were tested for morphological and behavioral effects before, during and after treatment. Fertility and hatchability data were collected during treatment only. Ferulic acid was shown to inhibit male copulatory behavior during treatment. Biochanin A inhibited male copulatory behavior during and after treatment. Neither drug affected female copulatory behavior though egg-laying was inhibited by the low dose of biochanin A. Ferulic acid significantly reduced the hatchability of eggs. Biochanin A increased the fertility of males and the hatchability of eggs fertilized by them. A correlation between results of this study and natural conditions of reproduction is discussed. It is concluded that both biochanin A and ferulic acid exert inhibiting influences on the reproductive behavior of Coturnix.