The 50-year-old Weiner, whose treatment began two days ago, is expected to report to the New York office daily, the union said in a statement.
“He looks forward to making a full recovery,” the union said.
The MLBPA gave no further details about Weiner’s illness and said it will announce medical updates when warranted.
“All of us look forward to Michael’s full recovery and to his continued contributions to our game,” baseball Commissioner Bud Selig said in a statement.
Weiner has a bachelor’s degree from Williams College and a law degree from Harvard Law School. He succeeded Donald Fehr as the baseball union’s executive director in 2009.
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