The adult Passerini's tanager is 16 cm long and weighs 31 g. The adult male is mainly black except for a scarlet rump, silvery bill and dark red iris.
The female has a grey head, olive upperparts becoming brighter and paler on the rump, brownish wings and tail and ochre underparts.
The female's plumage is the one that differs most from Cherrie's tanager.
Immatures have an orange tint to the underparts and rump, and look like a paler and duller female Cherrie's tanager.

The Passerini's tanager's call is a sharp wac.
Its song consists of a few clear pleasant notes, delivered in shorter phrases than that of its Pacific relative.
The adult Passerini's tanager is 16 cm long and weighs 31 g. The adult male is mainly black except for a scarlet rump, silvery bill and dark red iris. The female has a grey head, olive upperparts becoming brighter and paler on the rump, brownish wings and tail and ochre underparts. The female's plumage is the one that differs most from Cherrie's tanager. Immatures have an orange tint to the underparts and rump, and look like a paler and duller female Cherrie's tanager.
The Passerini's tanager's call is a sharp wac. Its song consists of a few clear pleasant notes, delivered in shorter phrases than that of its Pacific relative.
Scarlet-rumped tanager