Lower Kasimovian organic buildups in the Moleben-Iz section on the Ilych River, Northern Urals, were studied. Two levels of buildups development have been established, that are composing by algal and palaeoaplysinid boundstones and biocementstones. They are probably a part of long (up to 10 km) and complexly constructed biostromes. Lithological data indicate the formation of these buildups in the normal marine sutidal conditions on the carbonate ramp.