EN
The data presented in the paper indicate a probable lack of host specificity in Giardia and a number of species lower than that described to date. The common opinion is that three morphological groups should be recognized, represented by G. intestinalis (= G. duodenalis), G. muris and G. agilis. The diagnostics within these groups should be based on analysis of their isoenzymes or DNA fragments, and on antigene differences.