In music education, women are present in great numbers. In professional settings, however, women musicians are not as predominant. With some exceptions, such as Scandinavian countries, women still pursue gender equality in professional music practice. To inquire about the causes of this, we considered if gender-differences in amotivation in conservatoire instrument practice could be associated with aspects of learning environment. Self-determination theory (SDT) posits that learning environments may influence motivation, by satisfying or thwarting students' psychological needs and by selectively endorsing specific extrinsic goals. Thus, we analysed if-women and men-amotivation variations could be explained by differences in behavioural regulations and satisfaction of their psychological needs for competence and autonomy. Participants (67 women and 74 men, 18-47 years old) completed validated scales for amotivation, behavioural regulations, and needs satisfaction. Students exhibited high intrinsic and introjected regulations, and high autonomy and competence needs satisfaction. Students' identified regulation levels were modest, and external regulation and amotivation levels were low. Women students' perceived competence was lower, and their amotivation was higher than men's. Amotivation variations were explained positively by identified regulation and negatively by context-derived satisfaction of the psychological needs for competence (and autonomy, only among women). Results suggest that internalization of extrinsic goals can pose difficulties and that psychological needs satisfaction may counteract amotivation (autonomy being potentially more important for women musicians).