This study investigated whether motivation regulations mediate the relationship between socially prescribed and self-oriented dimensions of perfectionism and athlete burnout. Two-hundred and thirty-one (N = 231) elite junior athletes completed the Child and Adolescent Perfectionism Scale (Flett, Hewitt, Boucher, Davidson, & Munro, 2000), the Sport Motivation Scale (Pelletier, Fortier, Valle-rand, Tuson, & Blais, 1995), and the Athlete Burnout Questionnaire (Raedeke & Smith, 2009). Multiple mediator regression analyses revealed that amotivation mediated the relationship between socially prescribed perfectionism and burnout symptoms. Amotivation and intrinsic motivation emerged as significant mediators of the relationship between self-oriented perfectionism and burnout symptoms. The findings suggest that patterns of motivation regulations are important factors in the perfectionism-athlete burnout relationship.