Ines Diers started her career as a backstroke swimmer but eventually changed to freestyle . At the 1980 Olympic Games she won Olympic gold in the 400 free and in the 4×100 freestyle relay, adding two silver medals in the 200 and 800 free, and one bronze medal in the 100 free. One year later she won gold at the European Championships in the 400 freestyle and a silver in the 800 free. Diers twice broke the European record for the 400 metres freestyle, at the 1980 Olympics and at the 1981 European Championships in Split. She retired in 1982.