Ficus altissima is a large, evergreen forest tree with a buttressed trunk and a spreading crown, growing to 30 m (98 ft). The bark is smooth and grey, with small pale brown pustules. The branches are spreading and the twigs are hairy and often green when young. The leaves are alternate, elliptic to ovate, with entire margins and up to 100 by 40 mm (3.9 by 1.6 in). They are supported on short stalks and have sheathing stipules. The flowers are solitary or in pairs and are in the axils of the leaves. They are concealed inside hollow receptacles which grow into orangish-red, many-seeded. 25 mm (1 in) figs following pollination.