Offseason

• December 16, 1938: Ray Mueller
  Ray Mueller
  Ray Coleman Mueller was an American professional baseball player, a catcher in the Major Leagues from 1935–1944 and 1946–1951. Nicknamed "Iron Man," Mueller appeared as a catcher in every game the Cincinnati Reds played — 155 — during the wartime season...
  
   was traded by the Bees to the Pittsburgh Pirates
  Pittsburgh Pirates
  The Pittsburgh Pirates are a Major League Baseball club based in Pittsburgh, Pennsylvania. They play in the Central Division of the National League, and are five-time World Series Champions...
  
   for Johnny Dickshot
  Johnny Dickshot
  John Oscar Dickshot commonly known as "Ugly" Johnny Dickshot was a Major League Baseball outfielder for the Pittsburgh Pirates from 1936–38, the New York Giants in 1939, and the Chicago White Sox from 1944-45. He won the nickname "Ugly" because of his self-proclaimed status as the "ugliest man in...
  
  , Al Todd
  Al Todd
  Alfred Chester Todd was an American catcher in Major League Baseball. Born in Troy, New York, he played from 1932-1943 with the Philadelphia Phillies, Pittsburgh Pirates, Brooklyn Dodgers and Chicago Cubs....
  
   and cash.
• December 29, 1938: Al Simmons
  Al Simmons
  Aloysius Harry Simmons , born Aloisius Szymanski in Milwaukee, Wisconsin, was an American baseball player. He played for two decades in the major leagues as an outfielder, and had his best years as a member of Connie Mack's Philadelphia Athletics during the 1930's...
  
   was purchased by the Bees from the Washington Senators
  Minnesota Twins
  The Minnesota Twins are a professional baseball team based in Minneapolis, Minnesota. They play in the Central Division of Major League Baseball's American League. The team is named after the Twin Cities area of Minneapolis and St. Paul. They played in Metropolitan Stadium from 1961 to 1981 and the...
  
   for $3,000.

Notable transactions

• April 10, 1939: Johnny Dickshot
  Johnny Dickshot
  John Oscar Dickshot commonly known as "Ugly" Johnny Dickshot was a Major League Baseball outfielder for the Pittsburgh Pirates from 1936–38, the New York Giants in 1939, and the Chicago White Sox from 1944-45. He won the nickname "Ugly" because of his self-proclaimed status as the "ugliest man in...
  
   was purchased from the Bees by the New York Giants
  San Francisco Giants
  The San Francisco Giants are a Major League Baseball team based in San Francisco, California, playing in the National League West Division....
  
  .
• April 24, 1939: Oliver Hill
  Oliver Hill (baseball)
  Oliver Clinton Hill was a Major League Baseball player. He appeared in two games for the Boston Bees in , both times as a pinch hitter. In two at bats, he had one hit, a double, for a batting average of .500 and a slugging percentage of 1.000....
  
   was purchased from the Bees by the Milwaukee Brewers
  Milwaukee Brewers (minor league baseball team)
  The Milwaukee Brewers were a Minor League Baseball team based in Milwaukee, Wisconsin. They played in the American Association from 1902 through 1952.-A Milwaukee Tradition:...
  
  .
• August 19, 1939: Milt Shoffner
  Milt Shoffner
  Milburn James Shoffner was a Major League Baseball pitcher. He played seven years in the majors, from until , then again from until .Shoffner debuted in the majors with the Cleveland Indians in 1929 and pitched three seasons for them. In and 1931, his ERA was over 7.00, and by mid-season he was...
  
   was selected off waivers from the Bees by the Cincinnati Reds
  Cincinnati Reds
  The Cincinnati Reds are a Major League Baseball team based in Cincinnati, Ohio. They are members of the National League Central Division. The club was established in 1882 as a charter member of the American Association and joined the National League in 1890....
  
  
• August 31, 1939: Al Simmons
  Al Simmons
  Aloysius Harry Simmons , born Aloisius Szymanski in Milwaukee, Wisconsin, was an American baseball player. He played for two decades in the major leagues as an outfielder, and had his best years as a member of Connie Mack's Philadelphia Athletics during the 1930's...
  
   was purchased from the Bees by the Cincinnati Reds
  Cincinnati Reds
  The Cincinnati Reds are a Major League Baseball team based in Cincinnati, Ohio. They are members of the National League Central Division. The club was established in 1882 as a charter member of the American Association and joined the National League in 1890....
  
  .

Roster

Starters by position

Other batters

Starting pitchers

Other pitchers

Relief pitchers

Farm system