One of the best Dane players of his generation, Ehlers was drafted to the National Hockey League 188th overall in the 1984 NHL Entry Draft by the New York Rangers. He never however played in North America; he rather moved to the Elitserien in 1984 to join Leksands IF with whom he would spend 5 seasons before leaving for AIK IK and then Rögle BK. After a 1993-94 season split between his home club Aalborg IK and Swiss EHC Biel, Ehlers moved in 1994 in Austria to join the Klagenfurter AC. In 1997, he joined the Berlin Capitals of the DEL for five seasons; he would come back home in 2002 to play two last seasons with Aalborg IK before retiring.
Heinz Ehlers was a particularly prolific player in international competitions. At the 1990 and 1991 World Championships Pool C, Ehlers tallied respectively 22 and 25 points in merely 8 games each year. His strong showing helped the Danish National Team promote to the Pool B in 1992 where he kept being one of the very best player on the ice.
Today, Ehlers is the head coach of his former Swiss team EHC Biel.