After a season with HC Dukla Trenčín in the CSL, Demitra was selected 227th overall in the 1993 NHL Entry Draft by the Ottawa Senators.

He subsequently left Slovakia to join the Senators organization, spending three seasons split between team and their American Hockey League affiliate.

Demitra had his most successful seasons with St. Louis, being selected for three NHL All-Star Games and winning the Lady Byng Memorial Trophy in 2000.

Beginning in 1996, he played in six IIHF World Championships, winning a bronze medal in 2003 and captaining his country in 2011.

Initially a soccer player, like his father (who played professionally), Demitra only began to focus on hockey when he was 15.

[1] Demitra began playing at the senior level with ZŤS Dubnica in Czechoslovakia's second-tier league; he recorded 23 points (13 goals and 10 assists) over 28 games.

The following season, Demitra joined HC Dukla Trenčín of the premier Czechoslovak Extraliga in 1992–93, where he scored 11 goals and 28 points in 46 games.

Demitra mainly spent the season with Ottawa's American Hockey League affiliate, the Prince Edward Island Senators.

He played a game with HC Dukla Trenčín of the Slovak Extraliga, getting a goal and two points, before joining the Las Vegas Thunder of the IHL.

On 27 November 1996, the Senators parted ways with Demitra, as Ottawa traded him to the St. Louis Blues for Christer Olsson.

On 22 April 1997, Demitra scored his first playoff goal, beating Red Wings goaltender Mike Vernon, and added two assists in a 4–0 win over Detroit.

Demitra appeared in the 1999 NHL All-Star Game held in Tampa, Florida, scoring a goal for the World team in an 8–6 loss to North America.

Demitra played in the 2000 NHL All-Star Game held in Toronto, Ontario, where he scored two goals in a 9–4 World victory over North America.

He scored a hat trick and added two assists for a five-point game against the New York Rangers on 20 December 2000 in a 6–3 win.

On 30 December 2000, Demitra suffered an injury, however, he came back with the team late in the season, and appeared in 15 playoff games, scoring two goals and six points.

He had a four-point night against his former team, the Ottawa Senators, on 27 November 2001, scoring two goals and two assists in a 4–2 victory.

With the 2004–05 NHL lockout cancelling the season, Demitra signed with HK Dukla Trenčín of the Slovak Extraliga on 17 September 2004.

Demitra had three four-point games during the season, including one on 22 November 2005 against his former team, the St. Louis Blues in a 6–3 Los Angeles win.

Demitra played in his first playoff game with Minnesota on 11 April 2007, scoring a goal against Ilya Bryzgalov of the Anaheim Ducks in a 2–1 loss.

Demitra appeared in his first playoff game with Vancouver on 15 April 2009, recording an assist in a 2–1 win over the St. Louis Blues.

In the playoffs, Demitra had a three-point game against the Los Angeles Kings on 23 April 2010, helping Vancouver to a 7–2 win.

Slovakia was ranked in fourth place, as Demitra led the tournament in points with 10 and tied for the lead in assists with seven.

[11] The airplane caught fire and crashed shortly after take-off, a mere four kilometers from the Tunoshna airport.

Preliminary reports said that 43 of the 45 passengers on board had been killed, including the entire roster and four youth players,[12] and that the remaining one, Alexander Galimov, was in critical condition.

[1] Following his death, the elementary school in Dubnica nad Váhom which he had attended, and the ice hockey stadium in Trenčín where he started his successful career together with famous Slovak ice hockey players Zdeno Chára, Marián Hossa, Marcel Hossa and Marián Gáborík, were named after him.