Introduction: Child undernutrition is a major public health problem in Nigeria and other Sub-Saharan African countries. However, few analytical studies have quantified the role of risk factors. This study was conducted to determine the socio-economic and family related risk factors for undernutrition among children in Ibadan, Nigeria.

Methods: A case-control study was conducted among children100 cases and 200 controls aged 6-23 months. A semi-structured interviewer- administered questionnaire was used to obtain information on socio-economic status, infant feeding practices of the mothers, children's immunization status and recent episodes of common childhood illnesses. Bivariate and multivariate analyses were conducted to identify the risk factors.

Results: On bivariate analysis, the maternal factors associated with undernutrition were maternal level of education below secondary level, monthly income below $20 and polygamous marriage. Socio-economic factors significantly associated with malnutrition were residence in a high density area, family accommodation in a single room apartment and family weekly expenditure on food below $55. Children's characteristics associated with child malnutrition included incomplete immunization for age, recent episodes of diarrhoea and acute respiratory infection. The significant risk factors on multivariate analysis were maternal monthly income <$20, monthly household food expenditure <$55, residence in a one room apartment, higher birth order and incomplete immunization of the child.

Conclusion: The multiplicity of risk factors identified is indicative of the need for a multidisciplinary approach in developing preventive strategies child undernutrition.