Aquatic mosses are excellent bioindicators which show the grades of water quality and can operate as heavy metal accumulators. The object of this work was the physiological-biochemical characterization of heavy metal induced reaction of Fontinalis antipyretica considering proteinchemical, cellular, physiological and genomic aspects. The following damage in transport of electrons in PS II: Cu(II)>> Cd(II]) was detected by chlorophyll fluorescence measurements. Loads of Pb(II) and Zn(II) up to 100 µM had no detectable effects on the vitality. Experiments regarding the intracellular absorption of Cu(II), Cd(II), Pb(II) and Zn(II) showed a specific dependence on the heavy metal concentration of the medium and on the incubation period. The following priority was found within the range of concentration from 25 µM to 100 µM: Cu(II) > Pb(II) > Zn(II) > Cd(II). The compartmentation of Cu from the cytoplasm into the plastids and into the vacuole was detected due to the intracellular absorption of Cu(II). Potential Cu-bond partners are the SH-groups in the cytoplasm and the anorganic phosphate in the vacuole. Immunological investigations showed a constitutive expression of Metallothionein p2 homologous antigen, which was decreased specifically after a heavy metal loading for a period of three days. Furthermore a Cd(II), Cu(II) induced heat shock reply was proved. Due the Cu(II) load of 50 µM the increased biosynthesis of the glutamic acid and of cystein, a GSH-precursor, indicates the function as a metal chelator. An essential role of organic acids and phenolic bonds in the heavy metal homeostasis could be ruled out. A Metallothionein p1 homologous sequence was isolated from a genomic DNA of Fontinalis antipyretica and serving as a probe this sequence offers ideal pre-conditions to the clarify the regulation of genes similar to Metallothionein under heavy metal influence.