Prostanthera denticulata, commonly known as rough mintbush, is a shrub that is native to south-eastern Australia It has a low, spreading habit, growing to 1 metre high. The leaves are 4 to 10 mm long and 2 to 3 mm wide. The flowers are mauve or purple and appear in spring and early summer. The species was formally described in 1810 by Robert Brown. It occurs in New South Wales and Victoria.