Wind turbines are being designed in accordance with deterministic design rules. As wind turbines increase in size and power, these rules may not be adequate to ascertain a safe and well balanced design. Wind turbine industry can take advantage of the safety and reliability practices in e.g. aerospace, nuclear and offshore industry. These practices include System Reliability and Structural Reliability methods. The approach to introduce Probabilistic Safety Assessment (PSA), which incorporates these reliability methods, into wind turbine engineering, are described. The applicability, benefits and limitations of these methods are illustrated by means of two recent case studies. 5 figs., 2 tabs., 24 refs.