A total of 161 cultivars of soybean (Glycine max L. Merr.) were tested for their responsiveness to ethylene treatments, using senescence of the primary leaves and the induction of chitinase activity in the roots as response markers. Cultivar «Gong jiao 6308-1» showed rapid chlorosis and the highest chitinase induction upon treatments with ethylene. The inducibility of chitinase by ethylene increased with increasing age of the plant. In addition, it was found that upon repeated ethylene treatments nodule formation of cultivar «Gong jiao 6308-1» was completely blocked in the lower part of the root system when inoculated with Bradyrhizobium japonicum. In several other cultivars, e.g. in «Bai tie jia qing», ethylene treatments did not induce leaf senescence or induction of chitinase activity. Cultivar «Bai tie jia qing» also showed completely normal nodulation even after repeated ethylene treatments. These results demonstrate that different soybean cultivars show a wide variation and strongly differ in their ethylene responsiveness.