The purpose of this paper is to estimate and evaluate the relationship between environmental sustainability index and economic growth in developing countries. Most studies adopted Environmental Kuznets Curve (EKC) hypothesis as a methodology to deal with the impact of deterioration environmental quality on economic growth, to verify an inverted-U curve. In this paper Environmental Sustainability index (ESI) the index varies between zero to 100 in such a way that a higher index means a better Environmental Sustainability. This index which is opposite of the environmental deterioration index has been used and therefore expect a u-shaped Kuznets Curve in order to support Kuznets hypothesis. However, our findings regarding the estimated panel regression analysis during 2001-2005 contradicts the normal Kuznets Curve. In other word, we found an inverted-U curve regarding the relationship between environmental sustainability and economic growth.