High-molecular-mass PC complexes (PC-HMWCs) constituted by phyto-chelatins (PCs), cadmium and sulfide are synthesized by several organisms after exposure to cadmium. In this study, PC-HMWCs were isolated from photoheterotrophicEuglena gracilisand purified to homogeneity, resulting in compounds of molecular mass 50–380 kDa depending on the CdCl2and sulfate concentrations in the culture medium.