Water buffaloes ( Bubalus bubalis), are capable of becoming infected with Neospora caninum and Toxoplasma gondii, contributing to disease dissemination. The incidence of these antibodies was assessed in sera of water buffaloes, using an immunofluorescent antibody technique (IFAT). Any possible influence of breed or age of the buffaloes was investigated, besides assessment of sera antibody titres of any dogs and humans that were in close contact with the tested animals. Serum samples were taken from water buffaloes (n=411), dogs (n=8) and humans (n=14), from buffalo dairy farms in the São Paulo State, and tested. Of the samples of buffalo sera tested, 56.0% were reactive ( >1:200) to N. caninum and 49.9% were reactive ( >1:64) to T. gondii. Of all, 33.9% of the buffaloes presented antibody titres for both protozoon parasites. Of the canine serum samples, 25.0% presented titres ( >1:50) for N. caninum and 62.5% for T. gondii ( >1:16). The human serum samples did not show detectable antibodies for N. caninum when using a >100 limit titre for positive findings. The obtained data allows the conclusion that the protozoan parasite N. caninum, as well as T. gondii, are widely disseminated in the water buffalo herds assessed and, apparently, the factors breed and age do not interfere with frequency of N. caninum positives among adult female buffaloes. When concerning T. gondii, female buffaloes of 5 to 6 years of age showed more frequent presence of specific antibodies.