Six hybridomas secreting monoclonal antibodies directed against human fetal liver metallothioneins (MTs) have been generated and characterized. One antibody, K5A6, was specific for MT-1, the others recognized all isoMTs present in the human fetal liver. Each of these antibodies showed a unique cross-reactivity pattern when tested with MTs from the livers of different mammals. A double-antibody sandwich enzyme-linked-immunosorbent-assay (ELISA) was developed with the antibodies L2E3 and L5G2. This assay allows the detection of 60 pg human fetal liver MT and exhibits a metal dependent response for Zn-, Cd- and Hg-MT.