Incomplete IgG and IgA class immunoglobulins are formed in chronic brucellosis and these antibodies do not detect with classical Wright agglutination test (WAT). However these antibodies are measured with indirect Coombs and enzyme immune assay (EIA) techniques. In this study 90 patients serum samples were tested with WAT, indirect Coombs and EIA. All of the patients had chronic brucellosis. EIA was used to determine the levels of brucella specific IgG antibodies in 44 patients whose WATs were negative and indirect Coombs assays were positive and 46 patients whose WATs and indirect Coombs tests were negative. Thirty-seven (84.08%) of the 44 patients whose WAT negative and indirect Coombs positive were found positive for EIA IgG. Sixteen (34.7%) of the 46 patients whose WAT and indirect Coombs negative were found positive EIA IgG. The importance of EIA and indirect Coombs tests was discussed at the diagnosis of chronic brucellosis.