Born in Blaustein, Germany (then West Germany), Dieter Baumann was one of the few non-African athletes who were able to seriously challenge the African dominance of middle-distance running during the 1990s. Baumann was equally adept at both the 1500 m and 5000 m distances.
Although Baumann came second in the 3000 m at the European Indoor Championships in 1987, few considered him a medal chance at the Seoul Olympic Games10 000 m at the European Championships held in Budapest. He also tried to defend his title over 5000 m but did not even come close to winning a medal. In one of his last great races he set a new personal best over 3000 m in Monaco in 7:30.50 min in August 1998.
On October 19, 1999, Baumann tested positive for nandrolone and received a two-year suspension, thus missing the 2000 Summer Olympics. The exact circumstances of this episode remain unclear. Baumann was voluntary tested after the initial results by an independent institute. Extremely high levels of nandrolone continued to be found in the tests and the results of the tests fluctuated dramatically depending on which time of day Baumann was tested. After several weeks of voluntary tests, Baumann claimed that the results varied with the time of day because the nandrolone was in his toothpaste. The German Athletics Federation (DLV) reluctantly believed Baumann that someone had manipulated his toothpaste and allowed him to start at the German championships where Baumann qualified for the Olympic Games in Sydney. However, the IAAF did not agree with that verdict and imposed a ban. Baumann tried to sue the IAAF before a German court but was unsuccessful. Those defending Baumann have pointed to the fact that the levels of nandrolone found in his body were completely abnormal for any athlete wishing to enhance his performance. Baumann's opponents argued that he had no conclusive proof for his version of the story and could not name a suspect. After the ban, he came back in 2002, at the age of 37, and won another silver medal over 10000 m at the European Championships in Munich. Baumann participated in the 2003 World Championships in Athletics in Paris over 10000 m but did not finish the race. He retired in late 2003.