"Dave Eiland took a personal leave of absence and will be gone as long as he needs and that's all I'm going to share," Girardi said before the Yankees played the Blue Jays.
Bullpen coach Mike Harkey will serve as pitching coach while Eiland is away with batting practice pitcher Charlie Wonsowicz taking over in the bullpen.
"Obviously Dave is very valuable to us," Girardi said. "We're going to miss him. Just like when you have a player go down, people have to pick up and help out. Everyone will help out and we'll make it work."
This is Eiland's third year as New York's pitching coach and his eighth year with the organization. The 43-year-old pitched 10 seasons in the major leagues with the Yankees, San Diego and Tampa Bay. His last season was 2000.
Harkey is in his third season as bullpen coach and previously worked as Girardi's bullpen coach in Florida. He spent six seasons as a minor league pitching coach with San Diego.