We studied diet composition of red deer Cervus elaphus in the Bohemian Forest by micro-histological analysis of 207 samples of red deer faeces obtained on the Czech and the Bavarian side of the border. We carried out the research from October 2006 to February 2008, and collected samples every two months at nine monitoring plots that were situated at different altitudes (i.e. from 600 to 1,250 m a.s.l.). Our results confirmed the classification of red deer among intermediate feeders with a mixed diet of graminoids (29.4%) and concentrate food items (60.6%). Concentrate food items were dominant in their diet all year round; however, the diet composition during the winter season differed from the diet composition during the vegetation season. This change was mainly represented by the strong increase in consumption of coniferous trees (from 5.7 to 26.4%) during winter. The amount of graminoids in the diet was higher during the vegetation season, which was caused by the intensive consumption of graminoids at two top-hill plots (up to 90% per sample). Likewise bilberry, Vaccinium myrtillus, with ripe berries was identified as an important food source only at the mountain ridge (up to 33% per sample). In agreement with our prediction, the diet composition of red deer at windthrow gaps (Blatný vrch Hill and Schachtenau) differed from the diet composition at undisturbed forest sites. At the gaps, ferns were an intensively consumed food source (up to 80% per sample). Contrary to other mountain areas, ferns made up a much larger share of the diet not only during autumn and winter but also during spring and summer. At Schachtenau, red deer also fed extensively on bramble Rubus sp., which intensively proliferates at the gaps. Diet composition of red deer in the Bohemian Forest differed between seasons, between plots at the mountain ridge and plots situated at lower altitudes as well as between windthrow gaps and undisturbed forest sites. However, further research of diet selectivity is necessary to explain in detail the observed feeding patterns.