A male blue monkey (Cercopithecus mitis stuhlmani), a subspecies of the Sykes group, was purchased from a commercial trapper as an adult in July 1978 and kept at the Institute of Primate Research, Kenya, for 2 years. The animal developed acute respiratory distress and died. Small nodular foci were found in the lung at necropsy and diagnosed as bronchogenic carcinoma on histopathology.