In this study three types of adjuvants were used for preparation of potent antitetanic serum; Alum, incomplete Freund's adjuvant and Montanide ISA 206. Three groups of horses were used (each containing three horses), increasing amount of tetanus toxoid mixed with each adjuvant was given to horses weekly and blood samples were taken weekly until the titer starts to decrease. The group receiving Montanide ISA 206 gave the highest antitetanic serum titer (2200 Lf) after the third injection. While the group injected with incomplete Freund's adjuvant gave 860 Lf after the fourth injection. The group receiving alum gave the lowest titer (580 Lf) two weeks after the 4th injection. In conclusion: Montanide ISA 206 should be used as an alternative to routinely used alum and only for three injections.