Given the nature of non-governmental organizations and their reliance on volunteering, the leadership style plays a vital role in the formation, growth and survival of this type of organizations. The previous researches on this subject, reveal that the dominant leadership style of these types of organizations is servant leadership. This study is aimed at investigating what are reflections of using this type of leadership style in NGOs. In this study we also test the moderating role of Islamic work ethics. This study was conducted in Mahak institution which is a known Iranian NGO with 2200 employees. We selected 327 employees by stratified random sampling and distributed a standard questionnaire to collect data. For analysis of collected data, we used structural equation modeling, SPSS and smart PLS software. The results indicate that servant leadership has a significant positive relationship with four levels variables; individual (resilience and job involvement), team (team member interaction), organization (organizational identification and pride) and family (work family enrichment). Furthermore, we didn’ t find a positive relationship between Islamic work ethics (as a moderating variable) and servant leadership. Based on the research findings, the authors may suggest that NGOs board of trustees develop managers who tend practicing servant leadership style and provide them a platform for learning the characteristics of voluntary altruism, emotional healing, knowledge and a convincing role to take advantage of its individual, team, organizational, and family implications.