On April 23, 2012, Matsuzaka made his first rehab start for the Single-A Salem Red Sox. He gave up a home run in each of his first two innings, and gave up three earned runs in four innings against the Wilmington Blue Rocks, an affiliate of the Kansas City Royals. After stints with both the Portland Sea Dogs and Pawtucket Red Sox, Matsuzaka was activated to make his first major league start of the season on June 9 in Fenway Park against the Washington Nationals, where he allowed 4 earned runs in 5 innings. He would finish the year with a very unimpressive record of 1-7 with an 8.28 ERA in 11 starts before becoming a free agent.