Mature seeds of five cultivars of Asian rice (Oryza sativa L.), a variety of African rice (Oryza glaberrima Steud.) and two varieties of wild rice (Oryza perennis Moench and Oryza latifolia Desv.), cultured on 2, 4-D containing nutrient media showed rapid proliferation of the scutellum and high efficiency in morphogenic callus formation. Varying concentrations of sucrose were found to have different effects on callus growth and plant regeneration. High sucrose concentrations in the callus induction medium promoted callus formation and subsequent organogenesis. Callus produced by the cultivars and varieties of wild rice germinated in vitro and produced plantlets. Morphological evidence is provided to indicate that plant regeneration occurred through organogenesis. Aspects of interspecific relations are also discussed.