Background: Medical students are expressing increasing interest in international experiences in low-income countries where there are pronounced inequities in health and socio-economic development. Aim: We carried out a detailed exploration of the international service-learning (ISL) experience of three medical students and the value of critical reflection as a pedagogical approach to enhance medical students' conceptions of the Canadian Medical Education Directions for Specialists (CanMEDS) Health Advocate Role. Method: A phenomenological approach enabled us to study in considerable depth the students' experience from their perspective. Students kept reflective journals and wrote essays including detailed accounts of their experiences. The content of the students' journals and essays was analyzed using the critical incident technique. Results: Students noted an increasingly meaningful sense of what it means to be vulnerable and marginalized, a heightened level of awareness of the social determinants of health and the related importance of community engagement, and a deeper appreciation of the health advocate role and key concepts embedded within it. Conclusion: This in-depth phenomenological study focused on the detailed experiences of three students from whom we learned that social justice-oriented approaches to service-learning, coupled with critical reflection, provide potentially viable pedagogical approaches for learning the health advocate role. How this experience will affect the students' future medical practice is yet unknown.