Not quite 21 years old, she participated in the alpine skiing events at the 1948 Games. She won the silver medal in the downhill event behind Hedy Schlunegger. She also competed in the alpine combined, which consisted of one downhill run and two slalom runs.
Beiser placed second in the downhill portion of the event and eighth in the slalom portion. However, her total score was good enough to earn the gold medal. She thus became the first woman skier to win two Olympic medals, beating Gretchen Fraser to the honour by one day.
Between Games, Beiser married and began competing as Trude Beiser-Jochum. The combined event was eliminated from the Olympic programme, so, at the 1952 Oslo Games, Trude entered the downhill and the slalom. This time she won the gold medal in the downhill, beating Annemarie Buchner of Germany by nine-tenth of a second. She also finished in a tie for eighth place in the slalom.