C02 gas was supplied at a high concentration (3-5%) to the tissue culture chamber and its effect on shoot regeneration was examined in anther- and seed-derived calli of rice (Oryza sativa L.). The applicaiton of C0a2 was effective in both shoot and root regeneration. Furthermore, C02 supply reduced the necrosis of callus. When test tubes were capped with porous film in stead of aluminum foil, the regeneration rate was increased, in particular when C02 gas was supplied. Even when C02 was supplied, the addition of 3 % sucrose in the medium was more effective for the regeneration than 1% sucrose. By the C02 supply, plant regeneration was accelerated and the regenerated shoots became so vigorous that they could be safely and easily transplanted to soil.