To elucidate the cause of growth decline of pitch pine (Pinus rigida) in Seoul, tree density, tree age and physico-chemical properties of soils were investigated at 33 sites of pitch pine forests in metropolitan Seoul, its vicinity and rural areas. The physical properties of soils except for soil texture in Seoul did not differ from those in rural areas. pH values, base saturation, and Ca and Mg contents of soils in Seoul, however, were significantly lower than those in suburbs and rural areas. In contrast, soluble Al and $S0_4^{2-}-S$ contents in Seoul were higher than those in rural areas. Low pH of forest soils in Seoul and suburbs seems to be caused by acid deposition. According to multiple regression analysis, growth of pitch pine in Seoul was affected by several factors in the following order: soil bulk density < Al content of soils < tree density < Mg contents of soil < tree age. We concluded that the acidification of forest soil can be a predisposing factor for the growth decline of pitch pine in metropolitan areas.