He played in the National Hockey League between 1992 and 1999 with the Calgary Flames, Buffalo Sabres, and Chicago Blackhawks.

The rest of his career, which lasted from 1986 to 2006, was spent in the North American minor leagues and in Europe.

Internationally Trefilov first played for the Soviet national team at the 1991 Men's Ice Hockey World Championships and 1991 Canada Cup, where he shared goal tending with Alexei Marjin.

He started his National Hockey League career in 1993 with the Calgary Flames and he went on to spend time with the Chicago Blackhawks, and Buffalo Sabres.

His last club was the DEG Metro Stars of the Deutsche Eishockey Liga in Germany, where he played until 2006.