In the hepatic nucleus of the rat at least 2 nuclear globulin bands, identified by SDS polyacrylamide gel electrophoresis, are known to be influenced by thyroid hormones. In the present article a quantitation of these bands was obtained by scanning techniques. The effects of T3 were studied in male thyroidectomized (Tx) and intact rats. After sacrifice the hepatic nuclear globulins were prepared according to published methods. In Tx rats substituted with a single dose of 50 micrograms or during one week 2 micrograms T3 the t band decreased from 5.3% to 2.7% of the total nuclear globulin content which represent a complete normalisation. The n band did not show this rapid response to T3 as 2 micrograms given for one week only partially restored this band (Tx 1.4%, Tx + T3 2.2%). However during starvation of intact rats only the n band was slightly influenced by T3 as 2 micrograms of T3 partially prevented the decrease of this band seen in untreated euthyroid starving rats. The increase of the t band in starvation was not affected by T3. CONCLUSIONS the n and t bands are controlled by several factors, two of which are T3 and nutrition. The control of the t band seems to be dominated by the nutritional status of the animal. T3 seems to keep some activity on the n band, even in starved rats.