Some species of fungi growing on serpentine and calamine soils accumulate heavy metals in their mycelia and show poor growth in non-contaminated soil. This study tests the hypothesis that these fungi growing in heavy metal contaminated soil are tolerant and decrease the pollution from the soil. In present study, Pythium mamillatum Meurs and P. splendens Braun were isolated  from Ni and Pythium ultimum Trow from Zn polluted soils whereas only P. ultimum was isolated from non metal-contaminated soils. The effect of different concentrations of Zn and Ni on mycelial growth and biomass P. mamillatum, P. splendens and P. ultimum were studied. P. ultimum isolated from zinc contaminated soil was more tolerant than species isolated from non-contaminated or nickel-contaminated soil. P. mamillatum and P. splendens isolated from high nickel soil were more resistant to nickel than Pythium species isolated from non-contaminated or Zn-contaminated soil. The production of oospores of P. mamillatum was greater in Zn concentrations as compared to the P. ultimum isolated from Zn-contaminated soil. However, the comparative study of P. ultimum and P. mamillatum shows that the production of oospores increases with increasing Zn and Ni concentrations up to a certain level and then decreases.