1. Hyaluronic acid was detected as the largest glycosaminoglycan component in the glycosaminoglycan fraction from purified nuclei of regenerating livers as in the case of normal livers (Furukawa, K. and Tarayama, H. (1977) Biochim. Biophys. Acta 499, 278--289). However, the nuclear content of glycosaminoglycans tended to decrease after partial hepatectomy, reaching one-third of the normal liver level at 24--30 h after partial hepatectomy. On the other hand, two new polyanionic components were detected in the glycosaminoglycan fraction from regenerating liver nuclei. 2. One of these new components seems to be a sulfated glycopeptide. The 35SO4 incorporation into this component was stimulated biphasically after partial hepatectomy; the first stimulation occurring immediately after partial hepatectomy and the second stimulation occurring almost in parallel to the DNA synthesis. 3. Another polyacnionic component which also increases in the nuclear content after partial hepatectomy lacks hexuronic acid, sialic acid and 35SO4 and yet it is intensely stained by Alcian Blue. Preliminary investigations revealed the presence of hexose, ribose and phosphate as the major components. 4. In contrast to the primary localization of hyaluronic acid in the chromatin fraction and also in the nonhistone chromosomal protein fraction from it, these new polyanionic components were detected mainly in the karyosol fraction.