Power generation from wind energy is becoming more popular, having exponential yearly growth during the last decade. Furthermore, wind farm (WF) projects are now moving into complex utility scale power generation systems comprising of arrays of large wind turbines (WTs), whose development, installation and operation are constrained by extreme and hostile environments. However, this increases the need for through-life engineering service (TES) for WTs especially in offshore applications, where the operations and maintenance (O&M) becomes more complicated as a result of the harsh marine weather and environmental conditions. In this paper, TES of WTs is presented -identifying the current state-of-the-art in methods and applications, requirements and needs, challenges, and opportunities of TES in the wind sector. Also an illustrative case study on WT gearbox through-life support is presented to demonstrate the potential opportunities and applications of TES in the wind industry.