Kuznets hypothesis suggests that there is an inverted U-shaped relationship between economic development and income inequality. In this study, Kuznets' inverted U-curve hypothesis was tested using long-run time series data covering the period from 1978 to 2016 for Turkey. The long-run relationship between national income per capita and income inequality was investigated using Pesaran et al. (2001) ARDL bound test approach within the framework of two different specifications. According to the results of this study, there is an U-shaped relationship between national income per capita and income inequality for Turkey in contrast to inverted U-shaped argued by Kuznets.