[5] Lyashenko made his NHL debut with the Dallas Stars during the 1999–2000 season, seeing action in 58 games, while recording six goals and six assists.

He also spent time with the Stars' International Hockey League (IHL) affiliate Michigan K-Wings, notching five points in nine games.

[1] During his rookie season in the NHL, Lyashenko played center on the Stars second line, earning praise from coach Ken Hitchcock, "His game has risen beyond his years.

[9] On March 12, 2002, Lyashenko and Martin Ručinský were traded to the New York Rangers for Manny Malhotra and Barrett Heisten.

[10] During the 2001–2002 season, Lyashenko played for four different teams, the Stars and Rangers at the NHL level as well as the IHL's Grizzlies, and the Hartford Wolfpack of the American Hockey League (AHL).

He left his AHL team, the Hartford Wolf Pack, during their playoff run to join Russia at the tournament.

Wolf Pack general manager Al Coates was disappointed to lose Lyashenko from his club, but understood the decision: "Everyone wants to play for his country, and he shouldn't be portrayed as a bad guy.

While on vacation in Antalya, Turkey with his mother and sister, Lyashenko was found dead in his hotel room the morning of July 6, 2003.

[15] Reports by Turkish police confirmed this, stating that Lyashenko had left a suicide note and attempted to cut his arms and wrists before hanging himself.

[16] New York Rangers general manager Glen Sather said of Lyashenko, "Roman was a quality individual who had a positive impact on everyone he touched, both on and off the ice.

"[15] Dallas Stars general manager Doug Armstrong expressed similar sentiments: "Roman was a quality young man who we were privileged to have in our organization for three years.