David Vincent Segui, (; born July 19, 1966) is an American former Major League Baseball first baseman.
Segui was born in Kansas City, Kansas, the son of former Major League Baseball pitcher Diego Seguí. He played collegiate baseball for Louisiana Tech University and Kansas City Kansas Community College. During a 15-year baseball career, he played with the Baltimore Orioles, New York Mets, Montreal Expos, Seattle Mariners, Toronto Blue Jays, Texas Rangers and Cleveland Indians.
Segui was identified by Jason Grimsley as one of the players that have taken human growth hormone during his major league career (he was one of the players whose name was redacted on Grimsley's document). Unlike others, however, Segui had a doctor's prescription for HGH to counter a deficiency he had been diagnosed with, and had previously admitted to using them.
Segui has also admitted to using anabolic steroids during his career with the Mets, obtaining them from former clubhouse attendant Kirk Radomski. Segui never had any spikes in his performances or home runs, but says he knows about other ballplayers' usage. He was included in the Mitchell Report, which named people who were found using either HGH, steroids, or some other type of Performance Enhancing Drugs.