Ostertag played college basketball for the University of Kansas from 1991 through 1995 and made 258 career shot blocks during that time, a record for both Kansas and the Big Eight Conference, before being drafted by the Utah Jazz in 1995. He spent the next 9 seasons playing for the Jazz, playing along superstars John Stockton and Karl Malone, before being traded to the Sacramento Kings in 2004. His season with the Kings was a nightmare as he had little play time. On August 2, 2005, Ostertag was involved in a 5-team, 13-player trade (the largest in NBA history) that sent him back to the Jazz.

A little-known fact is that in 2002, he donated a kidney to save the life of his sister Amy Hall, who was dying of kidney disease [http://www.kusports.com/news/mensbball_archive/story/97727].