Interaction of cationic and amphoteric polyelectrolytes on the basis of vinylethynylpiperidol derivatives with polyacids, transition metal ions, surfactants, drugs, and dyes has been investigated. The influence of ionic strength of the solution and organic solvent additions on the behavior of the poly-electrolyte complexes is discussed. Study of such systems can be useful for understanding the important role of metal ions in living organisms, the nature of protein-lipid interactions, the mechanism of protein denaturation, etc.