Modified foragers represent a cost-effective option for harvesting high-density short-rotation energy plantations. However, new energy plantations grown in Brazil far exceed the stocking and the stem size characterizing plantations in the Northern hemisphere, which raises the question about the ability of modified foragers to perform effectively. A study was conducted on five eucalyptus plantations, located in different Brazilian States and spanning over a wide range of work conditions in terms of clone, age, planting density and row system (e.g. single or twin rows). Field stocking varied between 90 and 157 t ha-1, and breast-height diameter between 5 and 8 cm. The tests were conducted with a New Holland 9060 forager, equipped with a 130 FB energy wood header. This machine was capable of negotiating all test fields, and reached a productivity on these sites between 39 and 65 t h-1, which was comparable with the productivity values recorded in Europe and North America. The machine coped well with the high field stocking and stem size levels encountered in Brazil. Blockages accounted for a very small proportion of total harvesting time, which was similar to that recorded in studies conducted on poplar and willow in the Northern hemisphere. Productivity was directly proportional to field stocking and target chip length. Changing target chip length from 30 to 20 mm resulted in a 20-30% reduction in productivity. These figures reflect work conditions in uncoppiced first-rotation plantations, and they should be applied with some caution to following rotations.