Their backs are dull olive green, and they have a bright yellow-orange throat with a yellow chin; females are somewhat duller than males, and juveniles have black bills.

[3] The red-billed leiothrix was formally described in 1786 by the Austrian naturalist Giovanni Antonio Scopoli under the binomial name Sylvia lutea.

[8] Scopoli specified the type location as China but this was subsequently restricted to the mountainous regions of the Chinese province of Anhui.

[4][9] Five subspecies are recognised:[7] The leiothrix is about six inches in length, generally olive green, and has a yellow throat with orange shading on the breast.

[3] The edges of the wing feathers are brightly coloured with yellow, orange, red and black and the forked tail is olive brown and blackish at the tip.

[14][20] The species has also been introduced in Italy where three major populations can be identified (Tuscany and Liguria, Latium, Colli Euganei) and there are several areas at high risk of invasion.

[3] These birds have a song which consists of short powerful notes that are repeated continuously throughout the year but it is more persistent during the breeding season.

The males sing long complex songs with a wide array of syllables to attempt to attract the female.

[10] They are broad and blunt in shape with some gloss on the outside and they also have a pale blue colour and red like brown spots that encircle the larger end of the eggs.