Abstract
0·1% Protamine sulphate in normal (0·85% w/v) saline has been used as a diluent in Brucella serology instead of saline as such. The use of protamine sulphate in this concentration has obviated the need for performing the modified Coombs test to detect non-agglutinating Brucella antibodies. This method has been used in the Microbiological Diagnostic Unit of the University of Melbourne in the routine titration of 721 sera and has proved to give reliable and reproducible results.