The effect of 2-carboxythylgerumanium sesquioxide (Ge-132) as an interferon-gamma (IFN-gamma) inducer on post-surgical immunosuppression was evaluated from the immunological response augmented in canine neutrophils, macrophages and peripheral blood lymphocytes (PBL) using the chemiluminescence technique. Experimental gastrotomy was performed on dogs in two groups; one group was subjected to sham-surgery without any medication, and the other was treated by Ge-132 administration at 24 hr before operation. Although the phagocytic activities of neutrophils, macrophages and PBL in the sham-operated group were depressed transiently after surgery, those in the Ge-132-administered group (Ge-132 group) were enhanced for a long time after surgery. It appeared that the generated free radical, which blocked the phagocytosis of macrophages and PBL, was activated by IFN-gamma. These results suggest that Ge-132 pre-treatment may be efficacious and useful in preventing the multifaceted clinical symptoms induced by post-operative immunosuppression in dogs.