Beef stored at --18 degrees C for 20,25,32,153, and 183 days showed a diminution in the recovery of injected aflatoxin B1. An unusual passing of aflatoxin in ether and hexane fractions of silica gel column was noted. Ether fraction contained aflatoxin B1-like substance from stored beef samples. Probable occlusion of aflaton B1 to meat constituents due to physico-chemical changes associated with muscle during storage was discussed.