Born Poland (near Łódź), Regedziński was of German origin as his father, named Reger.
At the 2nd Chess Olympiad in The Hague 1928, he scored 10/13 (+8 –1 =4) receiving the third prize for the best individual result (no board order was known those days).
At the unofficial Olympiad in Munich 1936, where Polish team took the silver medal, he played at third board (+9 –2 =7).
In 1939, he played at fourth board, winning the individual bronze medal (+6 –3 =4) at the 8th Chess Olympiad in Buenos Aires.
[1] During World War II, he had played - as Theodore Reger - in a number of tournaments, including the 7th German Chess Championship at Bad Oeynhausen 1940, where he finished 10th.
In October 1941, he took 6th at the 2nd General Government chess tournament in Kraków/Warsaw (Alexander Alekhine and Paul Felix Schmidt won).
After the end of World War II, he returned to Łódź, was arrested by the newly appointed communist authorities and sentenced for collaboration with the fascist regime to serve four years in a labor camp.