Romanowski has been involved in numerous altercations with both teammates and opponents. In 1989, while with the 49ers, he had one with offensive tackle Harris Barton after Barton had taken exception to a hit Romanowski had made on wide receiver Jerry Rice during a practice session. In 1995, while with the Eagles, he was ejected from a game — and subsequently fined $4,500 — for kicking Arizona Cardinals running back Larry Centers in the head. Three more incidents occurred during the 1997 season while he played for the Broncos: In the first, he was fined $20,000 after his hit on then-Carolina Panthers quarterback Kerry Collins in a preseason game resulted in Collins sustaining a broken jaw; in the second, Romanowski spat in the face of 49ers wide receiver J.J. Stokes in a regular-season game played in December on a Monday night in response to Stokes' taunting; and in the third — in the AFC Championship game — Romanowski taunted Pittsburgh Steelers quarterback Kordell Stewart following an interception Stewart had thrown in the third quarter of the game, won by Denver. Two years later, while still with the Broncos, he was fined a total of $42,500 for three illegal hits plus a punch thrown at Kansas City Chiefs tight end Tony Gonzalez, and was also fined an undisclosed amount for throwing a football at Bryan Cox of the New York Jets, the ball hitting him in the crotch area.
In 2003, Romanowski injured one of his teammates, Marcus Williams, during a scrimmage. Williams, a backup tight end for the Oakland Raiders, was forced to retire after Romanowski crushed his eye socket with a punch. Williams took him to court seeking $3.4 million. Ronnie Lott and Jerry Rice, who had played with Romanowski, said that he had "crossed the line" in an admittedly violent sport. Williams was awarded $340,000. Though this was only a tenth of what he sought, Williams said that it was not really about the money but that he and his attorneys "just wanted to prove what was right and wrong about football".