Rhododendron macgregoriae is a rhododendron species native to Indonesia and Papua New Guinea at altitudes of 500–3,350 m (1,640–10,990 ft).

It is an evergreen shrub or tree purportedly growing to 15 m (49 ft) in height,[1] with leaves that are ovate-elliptic or obovate-elliptic, 40–140 × 25–50 mm in size.

The flowers are light yellow to orange.

R. macgregoriae is relatively easy to grow in cultivation and a popular parent for hybrid cultivars.

Today, nearly one hundred named cultivars are of "mac" descent.