One requirement for an oilseed crop to be considered for biodiesel production is that it provides a positive energy return compared with the energy used to produce the fuel. This in part depends on the energy input for the oilseed production. This paper studies the energy balance between the input and the output per unit area for a sunflower crop grown in Greece, in order to evaluate it as a source for biodiesel production. Calculation of the energy input was based on the operations and various inputs as used by farmers in Evros in the north of Greece. To estimate the energy required to produce the sunflower seeds, to manufacture fertilizers and pesticides and to produce and use the farm machinery, appropriate energy equivalents from the literature were taken into account. The energy outputs were estimated by simply multiplying the yield of sunflower seeds and stems by their corresponding energy value. The total energy input was calculated to be 10Á49 GJ ha À1 , with fertilizers being the major inputs. Assuming a typical sunflower seed yield of 1800 kg ha À1 , as obtained under normal conditions on fertile drylands, and taking into account the energy value of the seed, the net energy value was estimated to be 36Á87 GJ ha À1 and the ratio of energy outputs to energy inputs approximately 4Á5:1.