The practicum is a vital component emphasized in initial teacher training. This is when teacher trainees are given the opportunities to practice theory into practice. Providing mentoring support for teacher trainees by teacher mentors is important during the practicum. The purpose of this study was to investigate the impact of a mentoring program which initiated and implemented in two secondary schools in Sabah, Malaysia. A purposive simple of nine teacher trainees (mentes) and twelve teacher mentors consented to take part in this case study. Using a qualitative method research design, this study explored the in-depth mentoring experiences of both teacher trainees (mentees) and teacher mentors. Data collection tolos used were semi-structured interviews, focus group discussions, and document reviews (reflective journals). The multiple data sourcs were coded and triangulated to come up with the emergent themes from the study. The final results indicate that the impact of the mentoring program was varied but generaly positive for both teacher trainees (mentees) and teacher mentors. They gained from the mentoring program from different perspectives. Emergent themes that were significant for both teacher trainees (mentees) and teacher mentors were mentoring support in terms of providing pedagogical knowledge, skills and materials for teaching, developing and fostering mentoring relationships, the development of interpersonal communications, adjustment and building different personalities and attitudes, and reflective practices. In addition, both teacher trainees (mentees) and teacher mentors found peer coaching an important component in the mentoring process. However, as the mentoring process evolved during the practicum, some constraints identified were accessibility, availability and time. The study overall provides insights of the importance of providing mentoring support for teacher trainees (mentees) and teacher mentors during the practicum.