Purpose: The aim of this research is to examine the degree to which the quality and frequency of mentoring by cooperating teachers during practical teaching internship influence the professional competence of future teachers. Material: To verify our proposed object, we conducted a research using a questionnaire distributed, during 2016-2017 school year, The analyses are based on a sample of more than 164 Tunisian physical education trainees and 96 cooperating teachers who participated in a pre-test and post-test study. Results : The results indicate that the quality and frequency of mentoring explain the success of starting a professional life. In terms of learning, mentoring that follows helpful rather than transmissive principles stimulates the performance, motivation and job satisfaction of future teachers and reduces emotional fatigue. Conclusions: Cooperating teachers training should include supervision practice themes to provide their trainees with real practice opportunities and to support them as needed.