For the first time, data on the occurrence and richness of gall inducing insects and their host plants in a terra firme forestin the Oriental Amazon region, Porto Trombetas, Pará, Brazil are presented. In 1981 the mining company Minera o Rio do Norte, started a restoration project with native species in areas mined for bauxite. Samples of galls were taken in the dry and the wet seasons of 2002; in 36 reforested sites (from recently planted to 21 years) and in seven primary forest sites. Three hundred and nine different morphotypes of insect galls on 255 host plant species belonging to 45plant families were recorded. The most frequent galling taxa were Diptera of the Cecidomyiidae family (97%), followedby Coleoptera, Hymenoptera, and Lepidoptera. The host plant families most attacked by galling insects were: Fabaceae (87), Chrysobalanaceae (12), Burseraceae (18), Annonaceae (15), Clusiaceae (15), Euphorbiaceae (9), Melastomatacaeae (13), Malpighiaceae (17), Anacardiaceae (11), and Apocynaceae (7). The data indicate a high richness of gall inducing insects when compared to other vegetation types in Brazil (e.g., cerrado and Atlantic rain forest).