Isolates of Coxiella burnetii from different geographic regions in Europe, USA, Japan and Africa were compared in their binding properties to the monoclonal antibody (MoAb) 1/4/H directed against the lipopolysaccharide (LPS) of C. burnetii strain Priscilla. Immunoblot analysis and enzyme-linked immunosorbent assay (ELISA) revealed different binding patterns of C. burnetii isolates under study. Most of the isolates tested did react with MoAb 1/4/H. Only four of 20 groups of isolates and one isolate of an otherwise positively reacting group did not react with MoAb 1/4/H. The results indicate a significant variation of LPS structure of the C. burnetii isolates studied.