His father, Alexander Bielaski, a captain in the Union army, died at the Battle of Belmont.

A. Bruce Bielaski, head of the Bureau of Investigation, and his sister, Ruth Shipley, head of the State Department's Passport Division, were first cousins of Oscar.

Oscar learned to play baseball while enlisted in the Union Army as a drummer.

[1] Oscar Bielaski was inducted in the National Polish-American Sports Hall of Fame in 2005.

This biographical article relating to a baseball right fielder is a stub.