Summary A series of 950 photoscans of the liver with I 131 Rose Bengal were reviewed. Of 548 scans in which the diagnosis could be,confirmed by autopsy, laparotomy, or biopsy, 461 patients were correctly diagnosed by scanning; 333 cases were correctly diagnosed as positive and 128 cases were correctly diagnosed as negative. Of the 69 which were false positives, 55 showed diffuse pathologic processes such as cirrhosis or fatty metamorphosis of the liver. From 246 photoscans diagnosed as positive for space-occupying disease but for which no postmortem findings were available, 183 patients fulfilled other criteria confirming the presence of liver metastases at the time of the scan. In 98 patients in whom the scan was reported as normal and no postmortem findings were available, 65 patients were alive 3 years after the scan was performed and liver function tests did not suggest metastatic involvement of the liver.