The inhibitory effect of pooled canine serum on the growth of ten strains of Malassezia pachydermatis in vitro was investigated. Studies were also carried out to observe the effect of different concentrations of unsaturated bovine transferrin on Malassezia growth in vitro. Ten strains of Malassezia pachygedrmatis in normal canine serum (11.1%, 44.4%) were found to significantly inhibit the growth (p<0.0005) not only in a dose dependent but also in a time dependent manner. The same strains of yeast treated with 1, 2, 4 and 8 times the normal value of serum transferrin (3.0 mg/ml, 6.0 mg/ml, 12.0 mg/ml, 24.0 mg/fl), were shown to have significantly lower OD readings (p<0.05) when compared to yeast treated in lower concentrations of transferrin (1.5 mg/ml). The optical density (OD) of the ten strains of yeast were significantly lower (p<0.005) when treated with various concentrations of transferrin than with the saline control except at 72 hours post incubation. These results indicate that serum has inhibitory effects on Malassezia pachydermatis growth in vitro, and transfferin is one of the components that contribute towards this inhibitory role. The inhibitions are dose and time dependent.