Worldwide, there has been a steady growth in the use of wind power in recent years. The three key trends in wind turbines are noteworthy: 1) Production of bigger and more powerful turbines, 2) Increasing reliability and 3) Lowering cost of energy (CoE). Design guidelines for various components in wind turbine are generally considered well established. However, there is a constant push to develop wind turbines that require minimum maintenance or repair. Wind turbine lubricants play an important role in its operation, maintenance and reliability. Performance of turbine components such as main shaft bearings, gearbox, pitch and yaw gear drive, generator bearings and hydraulic systems depend greatly on the performance of lubricants under demanding operating conditions. This course will give an insight into the role of lubricant selection for different components in wind turbines. Various lubricants are used - such as gear oils for gearbox; greases for main shaft bearings, yaw bearings, pitch drive gears, pitch bearings and generator bearings and hydraulic oils for hydraulic systems. Improper lubricant selection or incorrect quantity can trigger reliability issues leading to substantial repair costs and equipment downtime. This course will also discuss challenges in evaluating lubricants for gearbox and main shaft bearing applications and suggest potential solutions.