Abstract.Alpha‐naphthyl‐isothiocyanate (ANIT)‐induced intrahepatic cholangitis was associated with significant polyuria in rats. The urine output in the experimental rats was about two and a half to four fold higher than that in the controls. The polyuria was accompanied by polydypsia and disappeared when water intake was limited and controlled. The glomerular filtration rate and renal histology remained intact. Dilution and concentration capacities were preserved and the response to exogenous anti‐diuretic hormone was intact. Following water deprivation, the water and electrolyte contents of the renal medulla and papilla were similar in both experimental and control rats. The excretion of a salt‐load in ANIT‐treated rats was delayed. It is concluded that the polyuria in ANIT‐treated rats is secondary to polydypsia. The finding of preserved dilution and concentration capacities in this experimental model contrasts to that in other experimental models of hepatobi