Asystasia alba is a species of tropical herb in the family Acanthaceae.

It is endemic to Christmas Island, an Australian territory in the north-eastern Indian Ocean.

Its specific epithet comes from the Latin alba (white), referring to the colour of its flowers.

Asystasia alba is an erect woody herb, growing to 0.5–0.75 m in height.

Its 30–140 mm long leaves are ovate, acuminate or acute, pale green in colour and usually bristly when young.