Pollicipes pollicipes is widely used as food and is the subject of intensive fisheries in Portugal. Since November 1990 growth of this species was studied on the SW coast of Portugal. Two kinds of methods were used: (1) individual growth: the adjacent substrata were marked with polyester resin and the organisms were mapped and measured (Rostro-Carina length=RC) every month; 2) spatial variability of allometric growth: various biometrical measures were used for animals from different habitats; the relationship between these values and the organic weight were established. The results of these analyses suggest that there are spatial (due to tide and light related factors) and temporal differences (growth rates arc higher in spring and summer) in the growth of this pedunculate barnacle. In this study RC was the biometrical variable that best represented the linear growth of this species and we recommend its use for fishery control purposes.