Plastic litter is gaining attention in environmental science, public perception, and, finally, in politics. Macro- and microplastic pollution of rivers, oceans, and beaches are regularly reported. However, to our knowledge nobody studied the temporal dynamics of plastic pollution at beaches. This study is a re-investigation of a former work done in 2012 on the occurrence, distribution and composition of microplastic at Slovenian beaches. Similar methods in field sampling and particle isolation were applied. The study was extended by including additional beaches, addressing seasonal aspects (winter and summer) and introducing quality assurance/quality control checks. Furthermore, the chemical composition of isolated plastic items was verified by ATR-FTIR spectroscopy. Only about 10 % of the putative microplastic items were decisively recognised as synthetic material. Secondary microplastics were present as fragments, fibers, films, and foams. Primary microplastics were absent at all. The microplastic concentrations of the present study were distinctly lower than in the former study. The low pollution of Slovenian beaches could be the result of regular beach clean-ups of touristic beaches, or an improved environmental consciousness of citizens and tourists. This study emphasize the importance of continuous microplastic monitoring to understand the annual microplastic contamination and its’ seasonal and inter-annual dynamics.