The aim of this study was to examine the effect of the endocrine environment of dominant follicles on the competence of bovine oocytes to develop from small antral follicles 2-5 mm in diameter. Twenty-seven pairs of ovaries with mature corpora lutea were obtained from a local abattoir. The mean diameter and wet weight of the corpora lutea of individual cows were 23.3 ± 2.7 mm and 4.7 ± 1.0 g, respectively. Follicular fluid was aspirated from large follicles more than 6 mm in diameter, and estradiol (E₂) and progesterone (P₄) concentrations were determined by a RIA. Ovaries were classified into each group of E₂-active-dominant (E₂-A-dom; E₂≧50 ng/ml and E₂:P₄ ratio>1); 12 pairs of ovaries, E₂-dominant (E₂-dom; E₂<50 ng/ml and E₂:P₄ ratio>1); 6 pairs of ovaries or P₄-dominant (P₄-dom; E₂:P₄ ratio<1); 9 pairs of ovaries. The concentrations of E₂ and P₄ in E₂-A-dom were 132.5 ± 97.6 ng/ml and 8.4 ± 3.5 ng/ml, in E₂-dom were 27.7 ± 9.7 ng/ml and 9.2 ± 3.7 ng/ml, and in P₄-dom were 4.2 ± 4.7 ng/ml and 98.5 ± 208.4 ng/ml, respectively. The mean number of small antral follicles, the mean number of oocytes fertilized, the rate of cleavage and of blastocysts in E₂-A-dom were 44.4 ± 20.3, 24.2 ± 10.9, 68.2%, 26.0%, in E₂-dom were 48.5 ± 11.9, 28.7 ± 8.6, 70.4%, 20.2%, in P₄-dom were 41.7 ± 24.0, 23.0 ± 15.3, 70.9%, 20.0%, respectively. There were no significant differences in the number of small antral follicles, the number of oocytes fertilized and developmental capacity of the oocytes among the groups. Results of the present study indicate that in cattle E₂ and P₄ in a dominant follicle do not affect the competence of the development of oocytes derived from small antral follicles.