This paper describes some effects on the load level of state-of-the-art multi-megawatt wind turbines introduced by the new edition of the standard IEC 61400-1:2005 ‘Wind Turbines—Part 1: Design Requirements’. Compared to the previous edition, the extreme load determination has been modified by applying stochastic and statistical analyses. Within this paper, the effect on the extreme load level of wind turbines based on the newly introduced load extrapolation and extreme turbulence model (ETM) is demonstrated and occurring problems are discussed. Load simulations have been carried out for four state-of-the-art multi-megawatt wind turbines of different design concepts and from different manufacturers. The blade root bending moments and tip deflection have been determined by applying different extrapolation methods. Advantages and disadvantages of these methods and tail fittings are discussed and interpreted. The obtained loads are partly compared with long-term simulations. The application of the ETM is demonstrated. The dependence of the load level on the turbulence intensity and control system, as well as the interaction with extrapolated loads, is discussed and limitations are outlined. The obtained load level is compared to the overall load level of the turbines according to the previous edition of the standard, IEC 61400-1:1999. Based on extrapolated loads, simplified methods are described to obtain loads without load extrapolation to reduce the effort for simulation and post-processing. Copyright © 2008 John Wiley & Sons, Ltd.