Other highlights of the deal include:

• Players will be required to play in the All-Star Game unless injured or excused.

• Instant replay will be expanded to include decisions on foul lines and traps, subject to an agreement with umpires.

• Players, managers and coaches may not use smokeless tobacco products during televised interviews and may not carry them in their uniforms.

• Players arrested for DWI will be required to undergo mandatory evaluation.

• Players will start wearing improved batting helmets manufactured by Rawlings by 2013.

An initial positive test for HGH would result in a 50-game suspension, the same as a first positive urine test for a performance-enhancing substance.

In addition, the number of offseason urine tests will increase gradually from 125 currently to 250 before the 2015 season.

"This was very important to me," baseball commissioner Bud Selig said. "This really is in everyone's best interest."

Random testing for HGH will take place during spring training and the offseason, but there is no agreement yet on random testing in-season. There can be testing at any time for cause.

"We've consulted with a lot of scientists on this, and we know there's a difference of opinion among scientists we've consulted," union leader Michael Weiner said. "We are sufficiently comfortable with the science to go ahead with testing, but we have preserved the right if there is a positive test for there to be a challenge -- if that's appropriate -- to the science at that point in time."

The sides will explore in-season testing, but the union wants to make sure it's done in a way that doesn't interfere with players' health and safety.

Blood tests will be taken on game days in spring training to see what effect they have on a player's energy level, a source told ESPN The Magazine's Buster Olney. Those samples will be discarded immediately. If the tests go well, MLB will proceed with HGH testing during the regular season.

Weiner said scientists told baseball the current blood test can only detect HGH in the blood from 48-to-72 hours.

"The players want to get out and be leaders on this issue, and they want there to be a level playing field," Weiner said. "The realities, though, are that baseball players play virtually every single day from Feb. 20 through October. And that's unlike any other athlete -- professional or amateur -- who's subject to drug testing. We want to make sure that we're doing everything we can on the HGH issue, but that it be consistent with not interfering with competition and not interfering with players health and safety under those circumstances."