Monocyte chemoattractant protein-1 (MCP-1) is a member of the C-C family chemokines, which mobilizes monocytes from bone marrow to the site of inflammation. To evaluate the clinical utility of canine MCP-1 as a blood test item, we measured serum MCP-1 concentrations in normal and ill dogs. Reference interval of canine MCP-1 was established as 115.6-176.9 pg/ml. Serum MCP-1 concentrations increased in the dogs affected with neoplastic (518.0 ± 84.8 pg/ml), inflammatory (257.0 ± 42.5 pg/ml) or other diseases (360.3 ± 45.2 pg/ml). The results showed high sensitivity of MCP-1 to detect neoplasia and inflammation. Moreover, MCP-1 increased in some cases in which C-reactive protein didn't increase. MCP-1 might be helpful as a screening blood test marker for detection of neoplasia and inflammation in dogs.