[N-[2-(2-oxo-l-imidazolidinyl)ethyl]-N’-phenylurea (EDU or ethylenediurea) was applied as a soil drench and as foliar sprays to evaluate protection from ozone injury in controlled fumigations on 44 species of herbaceous plants. At least 4 doses of EDU were compared on 5 plant species: Begonia cucullata var. Hookeri Willd., (fibrous rooted begonia), Tagetes erecta L. (marigold), Antirrhinum majus L. (snapdragon), Lycopersicon esculentum Mill, (tomato), and Chrysanthemum morifolium Ramat. (chrysanthemum). Protection from ozone injury was directly related to EDU dose up to about 500 ppm. The spray and drench treatments gave about the same protection from ozone. EDU had no measurable effect on plant growth. Genera showing relatively high sensitivity to ozone and good protection with EDU included Ageratum, Amaranthus, Browallia, Capsicum, Celosiay Dahlia, Lobelia, Lycopersicon, Nicotiana, Perilla, Salvia, and Zinnia. The EDU treatments used did not protect adequately Hedera Lactuca, Rosa, or Zea mays (sweet corn). Species of several genera showed little or no foliar injury even at the highest ozone dose (0.60 ppm/3 hr), including Brassaia, Catharanthus, Chlorophytum, Coffeay Cyclamen, Dizygotheca, Philodendron, Saintpaulia, and Torenia. ‘Fred Shoesmith’ chrysanthemum was insensitive to ozone.