Amastra tenuilabris is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae.
Subspecies: Amastra tenuilabris rubicunda <small>(Baldwin, 1895)</small>
The length of the shell attains 15 mm, its diameter 8 mm
The shell is dextral, ovate-conic, and slightly dull, marked with somewhat coarse growth striations. It is white, overlain by a tawny epidermis that tends to wear away below the suture on the body whorl. There are 5ý whorls, which are gently convex. The aperture is subquadrate, white, and shorter than the spire. The peristome is thin, and the columella is straight, featuring a small central fold. The lips are joined by a delicate, thin callus.
This species is endemic to Hawaii, occurring on Oahu island.