The study assessed the wind energy potentials of ten selected sites in the south western region of Nigeria and carried out the cost benefit analysis of wind power generation from the sites. 24 years’ (1987 to 2010) wind speed data at 10 m height obtained from the Nigeria meteorological agency were employed to classify the sites wind profiles for electricity generation. The energy cost analysis of generating wind electricity from the sites was also carried out. The outcome showed that sites in Lagos and Oyo States were adequately suited for large scale generation with average wind speeds ranged between 2.9 and 5.8 m/s. Those from other sites may be employed for small scale generation or engaged as wind farm with several small turbines connected together to generate large enough wind power. The turbine matching results shows that turbines cut-in and rated wind speeds of between 2.0 and 3.0 m/s, and between 10 and 12.0 m/s will be very suited to all the sites, particularly those in locations outside Lagos and Oyo States. The energy cost analysis also show that generation cost can be as low as Є0.02/kWh and as high as 5.03/kWh depending on the turbine model employed.