Upon single oral administration of 2-isopropylnaphthalene (2-IPN) (100 mg/kg) to rats, more than 95% of the dose was absorbed from the gastrointestinal tract within 24 hr. The maximum levels of 2-IPN in the blood, liver, kidneys, brain, heart, spleen and muscle were observed at 2 hr after the administration and then the levels decreased with time. However, the times taken to reach the maximum levels of 2-IPN in the adipose tissue and skin were longer than those in other tissues. The content and disappearance of 2-IPN in the adipose tissue were higher and slower, respectively, than those in other tissues. In addition, an extremely small amount of unchanged 2-IPN was excreted in the urine. In rats fed on the experimental diet containing 0.1% 2-IPN for 14 or 28 days, the 2-IPN content in the adipose tissue was much greater than that in other tissues. In the case of administration of the control diet for 1-21 days after feeding the experimental diet for 28 days, the 2-IPN contents in the adipose tissue and skin decreased progressively, However, the content and disappearance of 2-IPN in the adipose tissue or skin after continuous administration of 2-IPN were much lower and more rapid, respectively, than those of 2, 6-diisopropylnaphthalene. This suggests that the tissue accumulation of 2-IPN is low.