In the early going, he had to contend with his older brother Bobby's reputation as much as he did with the opposition. The two were compared endlessly with Dennis coming out on the short end. In his second year in the Windy City, Dennis was dispatched to play 40 games with the St. Louis Braves of the CHL. According to Hull, they were among the toughest games he ever had to play. It seems that many a minor leaguer figured that maiming a Hull might be just the right ticket to make the NHL.

He survived the attacks, however, and made his return to the Blackhawks in 1966-67. From that point onwards, he held a secure job at the NHL level. His offensive numbers became increasingly solid as many began to wonder who had the hardest slapshot, brother Bobby or perhaps Dennis. The consensus seems to ride with the latter of the two siblings. It is also thought that by the time Dennis had matured as a major leaguer, he would have been considered a star on most other teams across the league. But in Chicago, there was that huge shadow cast by "The Golden Jet."

Along the way, Hull eventually settled onto a line with Pit Martin and Jim Pappin. The trio gelled together as a finely balanced unit that could score goals and play great defense. In 1972, Hull got the nod to join Team Canada for the Summit Series against the Soviet Union. The experience counts among the highest points of his career, particularly considering that the Stanley Cup eluded his and his team's grasp for so many seasons when it appeared to be within reach.

Hull remained a fixture with the Hawks until 1977. It was at that time that family friend Ted Lindsay, then the GM of the Detroit Red Wings, asked Hull to jump to the Motor City. He did just that, playing one final campaign before retiring in 1978.