The increasing number of wind turbine power plant installations and the recent trend to locate them in proximity of build-up areas raise safety concerns as the rotor failure may result in blade throws that can endanger people living/working close to the wind farm. Therefore, it becomes strictly necessary to define setback distances and/or buffer zones to minimize the risk of damage or injury from components failure. However, according to the existing standards, buffer zones and/or setbacks distances are defined by 'rule of thumbs', usually based on the height of the wind tower, and are often overestimated, resulting in too large distances, which may result incompatible with the needs of increasing the number wind power installations. This explains why the scientific community is, now more than in the past, spending a lot of effort in the attempt of developing reliable methodologies able to assess the impact risk in the areas surrounding the wind farm. In the present paper a very novel and computationally efficient method is presented to estimate the blade throw hazard of wind turbines. The method combines a 3D dynamic model of the detached blade fragment with a rigorous probabilistic approach. Results are shown in terms of safe (white) and unsafe (dark) zones, which are estimated on the basis of an acceptable risk threshold. (C) 2012 Elsevier Ltd. All rights reserved.