The native and induced surface hydrophobicity of a number of natural sulfide minerals (galena, pyrite) were investigated by flotation tests in the absence and presence of EDTA. The dissolution behaviour of the minerals in EDTA solutions was studied as a function of pH and EDTA concentration. With the exception of sphalerite, the flotation and dissolution of the tested minerals in EDTA solutions depend strongly on the pH values and EDTA concentration. In general, at a proper EDTA concentration, low flotation and small amount of released metal species were observed up to pH 5 and > 10. In the range of pH 6-10, both flotation recovery and the dissolution of the minerals exhibited a plateau, and the amount of released metal species increased with increasing EDTA concentration. The floatability first increases with an increase in EDTA concentration; however, a further increase in concentration ( > 10 exp --3 M ) leads to a significant decrease in flotation recovery. Zeta-potential measurements show that, in the presence of EDTA, the iep of the sulfide minerals is shifted considerably to lower pH values. These results are used to discuss the surface hydrophobicity of the sulfide minerals.