It traditionally included populations that breed in Kamchatka, the Kuril Islands and Japan, but genetic and vocal evidence strongly suggested these should be treated as separate species, and are all now considered distinct with the Kamchatka leaf warbler in Kamchatka, Hokkaido and the Kuril Islands, and the Japanese leaf warbler in Japan (except Hokkaido).

Its single wing bar distinguishes it from most similar species except the greenish warbler, Phylloscopus trochiloides.

It is larger than that species and has a heavier, dagger-like bill, with a dark tip to the lower mandible.

This species occurs as an autumn vagrant in western Europe and is annual on Great Britain.

[3] The genus name Phylloscopus is from Ancient Greek phullon, "leaf", and skopos, "seeker" (from skopeo, "to watch").