Background & Objective: Currently, migration of rural population to cities and developing slums around them are main problems in population settlement that lead to imbalance in health standards such as difference in age groups death. The aim of this study was to examine factors associated with infant mortality in slums of the Ardabil city.

  Methods: This was a case- control study. All infants’ deaths from 2008 to 2010, which occurred in slums as a case, were included. For each case, tow controls, were chosen. Controls the ones who survived and were living in non marginalized area and years of birth and sex were matched in two groups. Information collected from health centers through questionnaires, interviews with parents and child death files.

  Results: The majority of mortalities (74.6%) were in neonatal period and 25.4% was in post- neonatal period. The most important causes of deaths in neonatal were prematurity (57%), and in post neonatal period were congenital abnormality (35.4%). Analysis of effective factors showed that birth weight, parents age and education, family income and occupation and smoking of father were highly associated with mortalities.

  Conclusion: Infant mortality of the family that their father is a smoker and they have low income, and low parental education level is significantly higher and should be taken into serious consideration to reduce the mortality.