Vincent S. Cullen, Warden A, will throw out the ceremonial first pitch at 10 a.m.
Then, nine of the 18 inmates on the team, half of them serving life terms, will take the field against the visiting San Francisco Bay Area Oaks/Cubs.
Runners will steal bases and pitchers will try to pick them off base. Pitchers might even throw inside to move a batter farther from home plate. It's allowed. It's part of the game.
The home opener is the first of 26 games scheduled against teams in Bay Area men's league through June but the season ends in August.
San Quentin State Prison's public information officer Lt. Samuel Robinson says the San Quentin Giants are looking for other opponents to fill out the schedule.
"We're always the home team. We have a perfect road record," Robinson laughed.
The prison has had a baseball team during the first half of the 20th Century, in the 1950s and again starting in 1995.
The team was the San Quentin Pirates until 2000 when they adopted the name of their professional counterparts across the Bay, Robinson said.
Mike Murphy, the San Francisco Giants' equipment manager, gave the San Quentin team the San Francisco Giants' practice uniforms.
The game is an outlet that allows inmates of different races, who normally segregate themselves in prison, to interact and develop camaraderie, Robinson said.
"This is a multi-cultural, eclectic group of individuals working together for a common cause," Robinson said.
The games also help foster an inmate's rehabilitation, Robinson said.
"It shows the inmates that people from outside the facility are still interested in their welfare, do not demonize them and are willing to interact with them," Robinson said.
And for a few hours on Saturday morning and Wednesday and Monday evenings it's not prison. It's baseball.