Anthers of Poncirus trifoliata (L.) RAF. (trifoliate orange, 2n=18) were cultured on the MURASHIGE and SKooG's (1962) medium containing 0.2 and/or 2.0mg/l of 2, 4-dichlorophenoxyacetic acid (2, 4-D), indole-3-acetic acid (IAA), oi-naphthaleneacetic acid (NAA), and kinetin in combination. Three weeks after planting, heart-shaped and cotyledonary embryoids appeared from the anthers. Embryoids were formed most efifciently from the anthers of early uninu-cleate stage, and on the media containing 0.2mg/1 of IAA. The callus formation was occurred on all media and was increased by the addition of 2, 4-D. Roots were induced by the transfer of the embryoids from the induction media con-taining growth regulators to the medium lacking growth regulators. From microscopic observation, some of these plantlets showed 9(x) chromosomes of haploid state and some of them had 10 (x+1), 11 (x+2), and 18 (2x) chromosomes. Besides these plantlets, mixoploids which had cells with different chromosome numbers in the same preparations, such as (9, 10), (9, 10, 11), and (10, 11) were obtained