Two recently developed approaches to the subisoform-specific detection and identification methallothionein (MT) isoforms are compared. They are based on the coupling of capillary electrophoresis with ICP MS and microbore chromatography with electrospray MS. The resolution of HLPC is judged to be slightly better since differently metaliated forms of the same sub-isoform can be separated. Detection by electrospray MS is mandatory to avoid the attribution of artefact signals observed in element-specific chromatograms to different sub-isoforms.Two recently developed approaches to the subisoform-specific detection and identification of metallothionein (MT) isoforms are compared. They are based on the coupling of capillary electrophoresis with ICP MS and microbore chromatography with electrospray MS. The resolution of HPLC is judged to be slightly better since differently metallated forms of the same sub-isoform can be separated. Detection by electrospray MS is mandatory to avoid the attribution of artefact signals observed in element-specific chromatograms to different sub-isoforms.