The purpose of this research was to study the influence of motivational climate perceived in peers and basic psychological needs (competence, autonomy and relatedness) on self-determined motivation and enjoyment in exercise. A sample comprised of 394 non- competitive physical exercisers, 156 women and 238 men aged between 16 and 54 (M = 21.64, SD = 7. 18), completed the Motivational Climate Perceived in Peers Scale, Scale of Motivational Mediators in Physical Activity, Behavioural Regulation in Exercise Questionnaire-2 and Physical Activity Enjoyment Scale. A correlation analysis between the variables studied, a confirmatory factor analysis (CFA) and structural equation analysis were performed. The results showed that the task- involving peer motivational climate positively predicted the three basic psychological needs (competence, autonomy and relatedness). In turn, meeting the needs for competence and relatedness positively predicted self-determined motivation, which also positively predicted the enjoyment the exercisers had during the activity. There were no significant associations between the ego- involving peer motivational climate and psychological needs. A multisample analysis indicated that the model was invariant across age and degree of exercise involvement. This study reiterates the importance of increasing exercisers’ self-determined motivation in order to obtain more enjoyment and to be more committed to the exercise. Therefore, it is essential to foster perceptions of competence, autonomy and relatedness by means of a task-involving climate. The findings provide evidence for the importance of peer motivational climate in sports motivation.