Although poplars are widely grown in short-rotation forestry in many countries, little is known about poplar growth performance in Sweden. In this study, above-ground biomass production was estimated for several hybrid aspen and poplar clones planted at different initial density at five locations across Sweden. Biomass assessments were based on allometric relationships between total above-ground woody dry weight and the diameter at breast height. According to a common harvest practice, tree biomass was partitioned into pulpwood and biomass for energy purposes. The percentage of pulpwood was strongly determined by clone for DBH >10 cm. The mean annual increment ranged from 3.3 Mg ha−1 yr−1 for balsam poplar in the north to 9.2 Mg ha−1 yr−1 for 9-yr-old ‘Boelare’ in southern Sweden. At the same age, hybrid aspen reached 7.9 Mg ha−1 yr−1. The results suggest that poplars and hybrid aspen are superior as biomass producers compared with tree species commonly grown on agricultural land at these latitudes. The r...