<p>Wind turbine design relies on the ability to accurately predict turbine ultimate and fatigue loads. The loads analysis process requires precise knowledge of the expected wind-inflow conditions as well as turbine structural and aerodynamic properties. However, uncertainty in most parameters is inevitable. It is therefore important to understand the impact such uncertainties have on the resulting loads. The goal of this work is to assess which input parameters have the greatest influence on turbine power, fatigue loads, and ultimate loads during normal turbine operation. An Elementary Effects (EE) sensitivity analysis is performed to identify the most sensitive parameters. Separate case studies are performed on (1) wind-inflow conditions and (2) turbine structural and aerodynamic properties, both using the National Renewable Energy Laboratory (NREL) 5-MW baseline wind turbine. The focus is on individual parameter sensitivity, though interactions between parameters are considered.</p> <p>The results of this work show that for wind-inflow conditions, turbulence in the primary wind direction and shear are the most sensitivity parameters for turbine loads, which is expected. Secondary parameters of importance are identified as veer, u-direction integral length, and components of the IEC coherence model (<i>a<sub>u</sub></i> and <i>b<sub>u</sub></i>), as well as the exponent (γ). For the turbine properties, the most sensitive parameters are yaw misalignment (θ) and outboard lift coefficient (<i>C<sub>l,t</sub></i>) distribution. This information can be used to help establish error bars around the predictions of engineering models during validation efforts, and provide insight to probabilistic design methods and site-suitability analyses.</p>