Studies on development in vitro of excised ovaries in the crosses of various cultivars in B. campestris×B. oleracea were carried out. Ovaries excised 4 days after pollination were cultured in vitro. The medium was composed of White's medium (1963) supplemented with 300mg/l of casein hydrolysate, 50g/l of sucrose and 8g/l of agar.Many seeds and well developed naked-embryos protruded from undeveloped seed coat were obtained in the capsules examined. These embryos were further cultured on the medium and many interspecific hybrid plants were obtained in various ultivars of B. campestris×B. oleracea.Production rate of hybrid plants was different in different subspecies of B. campestris used as female plants.Culture in vitro of excised ovaries on the medium with casein hydrolysate is useful as a new technique for production of interspecific hybrid plants in B. camestris× B. oleracea.