David Vincent Segui
- Bats Both, Throws Left
- Height 6' 1", Weight 202 lb.
- School Kansas City Community College, Louisiana Tech University
- High School Bishop Ward High School
- Debut May 8, 1990
- Final Game September 8, 2004
- Born July 19, 1966 in Kansas City, KS USA
David Segui is the son of former pitcher Diego Segui, father of Cory Segui, nephew of minor leaguer Dario Segui, and the brother of minor league Dan Segui. Dwight Evans played with both Diego and David Segui.
In June of 2006, Segui admitted to using human growth hormone as a player and that he discussed its use with Jason Grimsley. He also admitted to being one of the players implicated by Grimsley in the FBI investigation into PED use in major league baseball. However Segui used HGH legally with a doctor's prescription. As a result of his confessions, he was listed as a potential witness in the trial of Roger Clemens in the spring of 2012, as prosecutors claimed that back in 2001, their star witness, Clemens' former personal trainer Brian McNamee, had told him that he had saved needles used to inject Clemens. Segui initially did not want to appear at the trial, but Judge Reggie Walton issued him a subpoena, even though it was still uncertain whether Segui would in fact be allowed to testify, given that his testimony could be construed as hearsay. Judge Walton did in fact allow Segui's testimony, which took place on May 24th.