 In November 1933, the Philadelphia Phillies acquired Oana from Portland in exchange for cash, Frank Ragland, Jimmy McLeod, and a player to be named later. Portland manager Spencer Abbott noted that the deal required the Phillies to pay "$ 2500 for a look" and $ 20,000 if he was retained for the years. " Oana made his major league debut on April 22, 1934, becoming the fourth Hawaiian player to play Major League Baseball. He appeared in only six games for the Phillies, four as the starting left fielder. He compiled a .238 batting average with one double and three RBIs in 21 at bats. On May 1, 1934 the Phillies sent Oana back to Portland after less than 10 days in the big leagues.
