Objectives: This research investigated the role of marital conflict and family emotional security in children’s physical and psychosocial health. Method: 413 fifth-grade school children in the city of Tehran (220 girls and 193 boys) with a mean age of 10.81, were selected using relative stratified random sampling. Mothers responded to the Overt Hostility/ O’Leary-Porter Scale (OPS) and the Child Health Questionnaire-Parent Form (CHQ-PF-28) and children responded to the Security In the Family System (SIFS) scales. Results: The findings indicated that marital conflict and family emotional insecurity have inverse relationship with children’s physical and psychosocial health. Also, marital conflict was a predictor (inversely) of children emotional security. Conclusion: Marital conflict leads to an insecure attachment of children to parents.