Tumor necrosis factor (TNR) is an active component of serum from Corynebacterium parvum [Propionibacterium acnes] infected mice treated with [bacterial] lipopolysaccharide (LPS). To locate the production site of TNF, tried to block TNF production by using the following reagents; carrageenan, hydrocortisone and trypan blue. Following the injection of a large dose of carrageenan, administered before C. parvum treatment, TNF production was completely blocked. When administered after C. parvum treatment but prior to LPS injection, no blockage was observed. Injecting hydrocortisone before the LPS injection also blocked TNF release. This treatment, when administered before the injection of C. parvum had no observable influence on TNF production. A large dose of trypan blue, administered before the LPS injection, blocked the release of TNF. A low dose of trypan blue resulted in only partial blockage of TNF production. A large dose of trypan blue, administered prior to C. parvum treatment, partially blocked TNF production. Macrophage-enriched peritoneal exudate cells (PEC) from mice infected with C. parvum released TNF into supernatant after stimulation with LPS. The production site of TNF apparently is located within the activated macrophage and deeply related with lysosome.