Abstract: Background: Brucellosis is an important zoonotic bacterial disease of global health importance affecting different animals and man. Brucellosis control and eradication procedures are highly depending on accurate diagnostic tools and effective and safe vaccination programs. Rapid slide agglutination tests using different antigens as rose bengal antigen and Buffered Acidified Plate Antigen (BAPA) are considered as cheap, quick and effective tests for diagnosis and screening of brucellosis. Materials and Methods: With respect to packed cells volume and pH, specificity and sensitivity of 18 different slide agglutination antigens (rose bengal and buffered acidified plate agglutination antigens) prepared in Veterinary Serum and Vaccine Research Institute were evaluated. In the absence of bacteriological isolation, complement fixation test was used as a Gold Standard test. Results: No satisfactory differences with the results of rapid slide agglutination antigens with different pH and this may be due to narrow range of pH used in this study. However, when antigens of different packed cells volume were used, a high degree of sensitivity appeared especially when buffered acidified plate agglutination and modified rose bengal tests were carried out using antigens of cell concentration of 4 and 6%. In contrast specificity was decreased with antigens of less packed cells volume. Modified rose bengal and buffered acidified plate agglutination tests using antigens with cell concentration 4 and 6% showed lowest specificity. Conclusion: Results revealed that modified rose bengal and Buffered Acidified Plate Agglutination (BAPA) tests using antigens with lower cells concentrations than that of international standard are recommended to be used especially in animals of low anti-brucella titers and endemic areas with brucellosis especially when Brucella melitensis is the main causative agent. Modified rose bengal test and BABA test using antigens of cell concentration of 4-6% is recommended for diagnosis of B. melitensis infection.