The metabolic disposition of [2-14C]-centperazine (1; 3-ethyl-8-methyl-1,3,8-triazabicyclo[4.4.0]decan-2-one) following an injection of 5 mg/kg dose was studied in male albino rats. During the initial period of 45-60 min, a very rapid fall in blood level of radioactivity was noticed. Thereafter the rate of fall of blood radiocarbon went on decreasing but did not attain linearity even upto 24 h. The drug was found to be fairly distributed in all the tissues attaining highest concentration in most of them within 30 min. In 24 h, about 83.5% of the administered drug was eliminated from the body, of which 21.3% was recovered from the faeces and 61.1% from the urine. The 14CO2 accountes for only 1% of the total dose. The drug exhibited significant binding with all the tissues examined. The brain and muscle showed highest and lowest activity, respectively.