This paper investigates whether an inverted U relationship between pollution and economic development could be found in the Seoul metropolitan region using a panel data for the period of 1985∼1999. We uses a model with a more flexible random coefficients specification which allows for a greater degree of regional heterogeneity. The emissions of sulfur dioxidetotal(SO_2), suspended particulates(TSP), nitrogen dioxide(NO_2), and carbon monoxide(CO) were selected as four major pollutants. We found that the emissions of these pollutants per capita except sulfur dioxidetotal exhibited inverted U shapes with per capita gross regional domestic product (GRDP). We also noted that the turning points for Seoul metropolitan region occured at a range of incomes, from $3,000 to $5,000 per capita.