A powerful and tenacious forward, with good technique, who was well-known for his deft touch with his left foot, as well as his aerial ability, Salas had a prolific goalscoring record throughout his career; with 37 goals in 70 international appearances between 1994 and 2007, he is the Chilean national team's second-highest goalscorer of all time, behind only Alexis Sánchez.
He appeared for the Chilean national team at the 1998 FIFA World Cup in France, where he scored four goals in four matches, leading his nation to the second round of the competition.