The disposition of hexachlorobenzene (HCB) was studied in partially jejunectomized (middle section) or colectomized (excision of cecum and proximal colon) rats after iv or ip dosage (1.5 to 2.0 mg/kg). Excision of about 50% of the jejunum had no effect on body weight, feed intake, volume of urine, weight of feces, or urinary and fecal excretion of HCB as demonstrated by a comparison of sham-operated and jejunectomized animals. Similarly colectomy did not affect body weight, feed intake, volume of urine, or urinary excretion of HCB. However, the wet weight of feces was significantly higher and the amount of HCB in feces significantly lower in colectomized than in sham-operated rats. Hexadecane increased fecal excretion of HCB about two- to threefold without affecting its urinary excretion. The effect of jejunectomy and colectomy was similar in hexadecane-treated animals to that seen in untreated rats. Concentration of HCB in adipose tissue was significantly higher in colectomized rats than in sham-operated controls. Data represent in vivo evidence that the major site of nonbiliary, intestinal excretion of HCB is the large intestine.