The coasts of the largest inland marine areas (lagoons) of the Russian part of the Baltic Sea were studied in summer 2018-2019. “Marine litter sampling method” (IOW) was tested on the sandy beaches, including the assessment of macro-, meso- and large microlitter (¿ 2 mm) in the wreckline zone. This study was supported by the RFBR grant 18-55-76001, project “Litter rim of the Baltic coast: monitoring, impact and remediation” of the Project “ERA.Net Rus Plus”. In total, 14 beaches in the Kaliningrad region and 7 beaches in the Neva Bay (St. Petersburg) were examined, over 200 sand samples were analyzed where objects of anthropogenic origin were found (cigarette filters, ear sticks, foamed plastic, fragments of bricks/ceramics, plastic pellets and fragments, glass, rubber, metal). Plastic waste amounted to 67% on the beaches of the Kaliningrad region and up to 80% of the composition of microparticles in the NevaBay. The average concentrations of anthropogenic microlitter on the beaches of the Kaliningrad region were: Curonian Lagoon and Vistula Lagoon - 16 items/m2 and 6.3 items/ m2 of microlitter respectively. In the NevaBay, the concentration of marine litter is much higher: from 25-55 items/m2 of microlitter on the northern coast to 6-15 items/m2 on the southern coast, with microplastics dominating. In general in 2018-2019 the largest amount of litter of all fractions is found in the inner part of the estuary in the NevaBay despite the regular municipal cleanings of beaches. The remoteness of the beach from settlements is not associated with the amount of litter on the beaches. The main critical factors of litter migration in the coastal zone are wind speed and direction, wave heights, and shore exposure to wind. The studies confirmed the Frame method is applicability on the coasts of the Baltic Sea lagoons, but with limitations.