The league confirmed Friday that it is looking into the deal, but would have no further comment until the investigation is completed.
An Ottawa newspaper first reported Thursday night that the league is studying whether the contract circumvents the salary cap and the collective bargaining agreement.
"The Chicago Blackhawks vehemently dispute any implication that the team has in any way violated the collective bargaining agreement or had any intention whatsoever to circumvent the salary cap," the team said in a statement.
"The Marian Hossa contract is a legitimate contract that was approved by the NHL. We are not at all concerned by the investigation and are confident the NHL will conclude that there is absolutely no evidence that the Blackhawks intended to circumvent the salary cap."
Hossa's contract results in a $5.23 million cap hit each year over the length of the deal, according the report. That's despite a lot of the money being paid early in the contract with Hossa making $7.9 million annually for the first seven years before his salary tapers off.
The 30-year-old, who scored 40 goals last season with the Detroit Red Wings, is expected to miss the beginning of the season after having surgery on his shoulder.