The efficiency of several new groups of organotin (dibutyltin dithiocarbamates, tributyltin dithiocarbamates and tributyltin dithiocarbamate propionates) against wood-destroying fungi (Serpula lacrymans, Coniophora puteana, Coriolus versicolor) was tested. The best results were obtained from tributyltin dithiocarbamates, especially from tributyltin N-pyrolidine dithiocarbamate and tributyltin N,N-dialkyldithiocarbamate propionate. The total efficiency of these compounds was nearly the same as that of the commercially available products TBTN and TBTA. For the brown-rot fungus C. puteana, tributylin N-pyrolidine dithiocarbamate and tributyltin N-piperidine dithiocarbamate compounds were more effective than the standard commercial product TBTA even at the concentration of 0.0001 percent. The efficiency of dibutyltin dithiocarbamates was low both in comparison with the commercial standards and with tributyltin substituted compounds