Two- to 4-week-old seedlings of 10 eastern forest species [loblolly pine (Pinus taeda, wild and cultivated types), pitch pine (P. rigida), Virginia pine (P. virginiana), sweetgum (Liquidambar styraciflua), sycamore (Platanus occidentalis), white ash (Fraxinus americana), green ash (F. pennsylvanica), willow oak (Quercus phellos), sugar maple (Acer saccharum), yellow poplar (Liriodendron tulipifera)] were exposed to ozone at 0, 0.05, 0.10 or 0.15 ppm, and 2- to 4-wk-old seedlings of 7 tree species were exposed to ozone and/or NO2 at 0.10 ppm in 6 h per day exposures for 28 consecutive days. Loblolly pine and American sycamore exhibited significant growth suppressions, whereas white ash and yellow poplar exhibited significant growth stimulations when exposed to ozone at 0.05 ppm. Yellow poplar and Virginia pine were the only species that failed to show any significant adverse growth effects in response to the ozone treatment at 0.15 ppm. In several instances, significant growth effects were noted in the absence of foliar injury. NO2 alone significantly suppressed root and total dry weight of sweetgum. The only significant interaction effects noted between O3 and NO2 were less than additive.