induced by inhalation of CCI, gas 2 times weekly for 4 weeks. A partial hepatectomy was performed after Higgins and Anderson's method. Twenty four hours after the partial hepatectomy remaining liver weight was measured. H3-thymidin uptake ratio was counted in the tissue autoradiography. The liver weight was measured I, 2, and 3 months after sensitization. Results and Consideration: i. A regeneration of the liver cell was found to be suppressed by a sensitization with adjuvant and liver homogenate. 2. The uptake ratio of H3-thymidin in rats injured with CCh was high but it was low in sensitized group. 3. The liver weights were found to be decreased in both groups injected with adjuvant only and adjuvant plus liver homogenate. Therefore this suppression of the liver cell regeneration was thought due to the adjuvant effect.