The disposition of the beta adrenoceptor blocking drug 1-(2-cyclohexylphenoxy)-3-isopropylamino-2-propanol, exaprolol, in organs of the rat has been studied. After i.v. administration of 3H-exaprolol a transient extremely high accumulation of the drug in lungs was observed with a peak of 7.7% of dose/g 30 min post-administration. The disposition pattern in heart, kidneys and liver may be characterized by a tissue to plasma ratio about ten. Lower exaprolol tissue levels were observed after oral administration. The tissue to plasma ratios showed an initial increase followed by constant levels. The distribution of exaprolol in organs of the rat is discussed in the light of the previously determined pharmacokinetic parameters.