Snowy campion is an erect forb, 2-3dm tall with stems that are smooth or covered in very fine, short hairs. It has few, mostly axillary flowers, a greenish calyx, 1.5cm, and umbilicate. Petals are white, without auricles, and with oblong ligule-like appendages 1-1.6mm. Blades are cuneate, 8mm, 2-lobed or 2-cleft, it has 3 styles. Fruits are spherical, unilocular, capsules opening by 6 teeth, seeds are dark. Leaves are opposite, mainly or wholly cauline, sessile or short-petiolate, lanceolate or lance-oblong, 5-10cm long by 1-3.5cm wide.
It can be distinguished from other Silene species by its glabrous, inflated calyx and petals with ligule-like appendages.