Anthers of rice (Oryza sativa L., 2n=24) heterozygous for the waxy gene (wx+/wx) were cultured on medium supplemented with 2,4-D and with NAA and kinetin. Histological observation of the anthers thus cultured revealed that only the microspores underwent divisions leading to callus formation; the somatic tissues degenerated or remained quiescent. Upon transfer of callus to the differentiation media, plants with ploidy levels ranging from haploid to tetraploid were regenerated. Staining pollen grains with I2-KI showed that all the diploid and tetra-ploid plants were homozygous. Furthermore, in both ploidy levels the ratio of waxy to nonwaxy fits the expected 1:1 segregation ratio. Thus histological and genetic evidence indicates that all anther-derived plants obtained in this study are of microspore origin.