Rauvolfia sandwicensis ranges from trees to shrubs, standing 3–10(–13?) meters tall. It is distinguished by its milky sap and pale-colored bark, with short, stiff, and striate branches marked by conspicuous leaf scars and leaf axils featuring pectinate glands divided into 5–12 linear lobes. The leaves are simple and arranged in whorls of 3–5 per node. The blades, ranging from narrowly elliptic to occasionally broadly elliptic, or rarely oblanceolate or narrowly obovate, measure 6–16(–22) cm in length and (1.5–)2.5–6(–6.5) cm in width, with an acute apex and glabrous surfaces. The leaf margins are entire, and the petioles span 1.5–4.5 cm in length, accompanied by small, deciduous stipules and persistent glands in the leaf axils. The flowers are borne in compound cymes, initially terminal but soon appearing lateral, with peduncles of 1–6 cm and pedicels of 0.5–2 mm. The flowers are bisexual, featuring a campanulate, 5-lobed calyx with broadly ovate lobes and a salverform corolla with a 3–10 mm long tube. Stamens number five was inserted into the corolla tube. The ovary is superior, leading to bilobed, green drupes that turn purplish black upon maturity, measuring approximately 8–16 mm in length and 6–20 mm in width, with strongly flattened seeds; ca. 1 cm long; 0.5 cm wide. It occurs on ridges, slopes, and gulches and is also found in Lantana thickets and lava flows between 100–550(–800) meters.