PURPOSE: To evaluate the clinical significance of renal excretion of oral Gastrografin in gastric resectionpatients. MATERIAL AND METHOD: Seven days affter gastric resection, eight normal volunteers and 30 patientsunderwent abdominal and CT scanning before and 1-1.5 his after oral administiration of Gastrografin. Theattenuation coefficients of the bladder were measured and the maximal attenuation difference between pre-andpost-gastrografin administration was calculated. RESULTS: In the control group, there was no abnormal renalexcretion of oral Gastrografin, though in 83 % of patients(25 of 30), this was demonstrated as focal increase inthe density (> or = 20 HU) of the bladder and/or collecting system, or ureteral opacification. Mean maximal densitydifference was 84.4+/-82.9HU in the patient group (n=24), with renal excretion of enteral Gastrografin and,3.5+/-4.4 HU in the control group (n=7), with statistical significance (Student's t-test, p<0.01). No patientshowed either radiological or clinical evidence of direct leakage from the suture site. Patients who underwenttotal gastrectomy showed a higher maximal density difference than those in whom gastrectomy was subtotal. CONCLUSION: Unless direct leakage is visvalized on fluoroscopy or spot films, renal excretion of oralGastrografin should not be regarded as a sign of anastomotic leakage. Situations other than leakage, e. g.increased mucosal permeability or absorption, or increased bowel transit time in postoperative duration, should beconsidered as possible causes.