A new method is proposed for the microtitration of CBPP vaccines by performing eight parallel endpoint two-fold dilutions. When performed on a 96-well plate, it gives a titre with a precision of ± 0·2 log 10 . By comparison, the established method, performed in tubes, gives a precision of only ± 0·6 log 10 . The adaptation to microtitre plates allows much more economical culture of larger numbers of samples. Statistical analysis permits determination of vial-to-vial homogeneity of a batch and calculation of a titre with a precision of ± 0·09 log 10 . The new method may be applied for the titration of mycoplasmas.
