Lateritic nickel ore from the Sukinda Mines, Orissa, India, was leached using Thiobacillus ferrooxidans, Bacillus circulans, Bacillus licheniformis and Aspergillus niger at 5% (w/v) solid: liquid ratio for 5¨C20 days. Maximum leaching of Ni was achieved with B. circulans (85%) and Aspergillus niger (92%) after 20 days. Bacillus circulans showed significantly higher rate of leaching than the other organisms giving 80% Ni extraction after 15 days. The importance and usefulness of heterotrophic organisms in metal extraction are discussed.