The paper analyzes the clinical and laboratory features of Lamblia infection in children living under long-term low-dose chemical load. The scientific search methodology comprised the meticulous examination of the patients randomized by the presence or absence of protozoonosis and the statistical processing and expert analysis of the results. The comprehensive approach could define the main signs of the pathomorphism of lambliosis in the areas with high anthropogenic loads and identify immunological disorders, intoxication, and hepatobiliary dysfunctions. The impact of environmentally induced chemical contamination of the biosphere on the natural history of protozoonosis should be borne in mind when evaluating the biological hazard and risk of environmental biological factors on the population health and when scheduling and implementing hygienic and sanitary-and-epidemiological measures to prevent lambliosis in the high anthropogenic load areas.