Long-term exclusion of deer may decrease some plant species through interspecific competition. I studied the effects of deer exclosures for 16 y on tall forbs and tree saplings inside and outside three exclosures of beech forest in the Tanzawa Mountains, eastern Japan. Understory cover ranged from 69% to 95%, and herb-layer height ranged from 1.1 to 1.4 m, inside and outside the exclosures. The density of 2–4 of 18 targeted tall forb species was significantly greater inside than outside the exclosures (Mann–Whitney U-test, P < 0.05). No species showed a higher density outside the exclosures. Mature ramet density of tall forbs was greater inside than outside exclosures, with the exception of two species. No clear relationship between forb densities and those of tree saplings was observed. The maximum height of saplings of most tree species exceeded the height of the herb layer. The mode of tree sapling height was 1–2 m and the tree density ≥2 m in height was 2260–5400 ha^–1, whereas no tree saplings >1 m in height were observed outside the exclosures. The results suggested that deer exclusion for 16 y maintained growth of tall forbs and concurrently promoted establishment of tree saplings, and almost no suppression of forbs and tree saplings was induced by the dense understory.