In 1987, Busch won the 400 m title at the World Indoor Championships in Indianapolis. The highlight of her career came at the 1987 World Championships in Rome, where she won a clear victory in the 400 m hurdles in 53.62 secs, to become world champion. She won a second gold medal in the relay with Emmelmann, Neubauer (Rubsam) and Muller. At the 1988 Olympic Games in Seoul she finished fourth in the final of the 400 m hurdles, being edged out of the bronze medal by her GDR teammate Ellen Fiedler (53.63 – 53.69). She did win a bronze medal in the relay alongside her teammates Neubauer, Emmelmann and Muller.