The present study was designed to investigate the effect of experi mental hypothyroidism induced by subcutaneous injection of methyl thiouracil (MTU) on the morphological and morphometrical changes in the liver of the rat. Fifty rats were used in this experiment. They were divided into four groups A,B,C and D and injected by subcutaneous route with methylthiouracil at a dose level of 10, 0.5, 0.2 and 0.1 mg. per kg. body weight respectively. In addition, a fifth group (E) of 10 rats was used as a control. The histopatholo gical examination revealed pronounced congestion together with focal degenerative changes. The morphometrical changes were char acterized by an increase in the nuclear diameter of hepatic cells in the first two groups.