This paper is the first in a series being prepared prior to the publication of the flora of French Polynesia. Taxonomic novelties are made in the following families: Euphorbiaceae, Piperaceae and Urticaceae. Recent fieldwork and collections particularly those arising from a survey undertaken by ORSTOM (1982-1994), have made it possible to describe the following eleven new species: Chamaesyce fosbergii Florence, C. sachetiana Florence, Glochidion grantii Florence, G. nadeaudii Florence, G. papenooense Florence, G. rapaense Florence, G. tooviianum and Macaranga huahineensis Florence (Euphorbiaceae); Peperomia oliveri Florence & W.L. Wagner and P. tooviiana Florence (Piperaceae); Pipturus schaeferi Florence (Urticaceae). Four new combinations are established.