In 1951 an informative hydrobiological observation was made on the reservoir Vranov, organized by the secondary school, Znojmo, under the direction of Dr. F. Brychta, professor. This work included also samplings performed to estimate the composition of Testacea in this reservoir. Up to this date no Testacea had been estimated here. On the whole 37 samples were collected altogether along the length of 30 km of the reservoir and at different depths. The material was treated with the use of a common procedure (Štěpánek, 1963). Quantitative estimations were made in 13 samples. The total of 1,353 individuals were inspected and measured, belonging to 47 genera, 121 species, 34 varieties, and 15 forms, resp. From this 1 genus, 20 species, 12 varieties, and 7 forms, resp., are new for the world fauna of Testacea.