The application of micromodification of mercaptoethanol agglutination test to the serologic diagnosis qf Br. canis infection was evalZlated. The prevalence of antibodies to Br. canis and Br. abortııs in three different groups Of dogs was also inı'estigated. Sera were compared by AfA- TA T ( Mercaptoethanol Tube Agglııtination Test), ME-MAT (Mercaptoethanol MicroAgglutination Test) MA T (Micro Agglutination Test) for agglutinins to Br. canis alZd tested h)! MA T for agglııtinins to Br. abortus. A titer of i:200 in M E- TA T was considered as indicative of active Br. canis infection. This titer corresponded to i:40 in ME-MA T. All results of ME-MAT correlated well with those of Af E- TA T. MATfor Br. canis infection did not give reliable result. Of 222 sera examined, 14 (6.3 %) had a titer of 1:200 or more and these were considered as active Br. canis ilZfection. None of the military service dogs were positive for Br. canis whereas 15.6 % of stray dogs and 4.5 % of pets were positiDe. In AfA T for Br. abortus, afew of sera gave positive reaction at low titer, and these were considered as negative test result.