Reformation of public health system financing in Russia requires the use and distribution of the most effective and least expensive diagnostic and medical methods. Giardiasis is the most common human anthroponosis. The diagnosis and treatment of this disease call for considerable funds of the budget, medical insurance companies, and the patient himself/herself. The paper gives the results of the clinicoeconomic analysis aimed at detecting the most rational frequency of diagnostic studies. The analysis provides evidence that triple coproprological study has the greatest advantages. The findings make it possible to recommend just this study for wide use in the diagnosis ofgiardiasis.