Dissertation (MSc Pediatric Nursing)Background: The problem of orphans is sensitive all over the world and causes challenge in caring and protection of their right and prosperity (UNICEF, 2017a). This study, intended to determine the effect of orphan institutionalization on child deprivation, child maltreatment and quality of life among the orphaned children in Zanzibar. Methods: Analytical cross-sectional study design was employed. Simple random sampling was used to select 374 participants from all five regions of Zanzibar. The study included both children aged 7 to 18 years living in institutions and those living in a home environment with their guardians. Child Orphan and vulnerable children wellbeing tool was used to measure child deprivation. Child traumatic questionnaire were used to measure child maltreatment and World Health Organization quality of life questionnaires were used to measure quality of life. Both descriptive and inferential analysis was conducted by using SPSS version 20 Results: Out of 374 participants 53.7% (201) were female, the mean age was 13 (SD=3.281), and 28.6% (107) were institutionalized in orphanage centers. 129 (34.5%) children were deprived on nutrition, 106 (28%) on education and 178 (47.6%) on health. Also 69% (258) experienced physical abuse, 61.4% (230) emotional abuse, and 4.8% (18) sexual abuse. After adjusting for confounder, being institutionalized was associated with nutrition deprivation (AOR 3.516, 95% CI 3.441, 5.322), education deprivation (AOR 3.509, 95% CI 1.801, 6.835), heath deprivation (AOR 2.464, 95% CI 1.300, 4.670), physical abuse (AOR 2.282, 95% CI 3.826, 5.039) and poor quality of life (AOR 3.713, 95% CI 1.952, 5.064). Conclusion: Child deprivation, child maltreatment and quality of life orphan still are problems which face institutionalized orphans in daily life.