|1991 Tokyo||10,000 m|
|1993 Stuttgart||10,000 m|
|IAAF World Half Marathon Championships|
|1995 Montbéliard||Half marathon|
|1997 Košice||Half marathon|
At the 1993 World Championships in Athletics in Stuttgart he finished second after a controversial incident on the final lap in which he lost one shoe after making contact with the eventual winner Haile Gebrselassie. He also won the 100th Boston Marathon in 1996 as well as the 102nd Boston Marathon in 1998. Tanui won IAAF World Half Marathon Championships in 1995 and silver in the 1997 competition.
He was the first athlete to run a half marathon in less than one hour by running 59:47 in Milan on 3 April 1993 and improved the previous world record by remarkable 59 seconds. His record was broken five years later by fellow Kenyan Paul Tergat.
At the Chicago Marathon in 1999, Tanui helped spur Khalid Khannouchi to a new world record, eventually finishing 2nd in 2:06:16, which was a Kenyan national record and the third fastest marathon in history at that point.
He was involved in a serious car accident near Nakuru in February 2010 suffering major injuries to his leg and chest. David Lelei, another former runner, was driving Tanui's car and died in the accident.
- All results regarding marathon, unless stated otherwise
|1996||Boston Marathon||Boston, United States||1st||2:09:15|
|1998||Boston Marathon||Boston, United States||1st||2:07:34|
|1999||Chicago Marathon||Chicago, United States||2nd||2:06:16|
|2000||Chicago Marathon||Chicago, United States||3rd||2:07:47|
|2002||Vienna Marathon||Vienna, Austria||1st||2:10:25|
|Men's Half Marathon World Record Holder
1993-04-03 – 1998-04-04
|Men's Half Marathon Best Year Performance