Lassi Parkkinen made his international début before World War II, taking part in both the 1937 and 1938 World All-around Championships, but not very successfully. Parkkinen continued to skate through World War II and won the 1947 World All-around Championships, while placing first in the 5,000, second at 10K and third in the 1,500. In 1947 Parkkinen was also selected as the Finnish Sportsman of the Year. Parkkinen’s next international competition was the 1948 Olympic Winter Games, where he won silver in the 10,000 and was fourth at 1,500. The next internationals were not very successful for Parkkinen, as his all-around finishes at the 1950 and 1952 European All-around Championships were fifth and fourth, although he won 500 silver and gold, respectively. But at the 1952 World All-around Championships Parkkinen won silver in all-around and won his fourth (silver in 5,000) and fifth (bronze in 10,000) world distance medals. Parkkinen also won the Finnish all-around title in 1941, 1943-44, 1946 and 1952. After his competitive career Parkkinen was the vice-chairman of the Finnish Skating Federation from 1954-60 and a committee member of the International Skating Union from 1957-64.
Personal Bests: 500 – 43.9 (1952); 1500 – 2:19.6 (1948); 5000 – 8:25.1 (1952); 10000 – 17:25.7 (1946).