Objective: With improved and sustained efforts in the prevention and management of pneumonia, diarrhea and vaccine preventable diseases, neonatal mortality is increasingly becoming a major contributor to childhood mortality particularly in developing countries. Evaluation of neonatal mortality pattern is an essential step in the effort to curb its incidence. We therefore, set out to determine the neonatal mortality pattern and its associated factors in a tertiary hospital in southern Nigeria. Methods: This is a retrospective study of neonatal mortality in a tertiary hospital from August 2004 to July 2007(a 3 year period). Data obtained include total live births, neonatal deaths, relevant information on pregnancy, labour and delivery, neonatal morbidity and duration of life. Results: There were a total of 3,051 live births and 44 neonatal deaths with a neonatal mortality rate of 14.4/1000 live births. Early neonatal mortality constituted 81.8%of over all neonatal mortality with the major causes being prematurity 40% severe birth asphyxia 29.5%and neonatal sepsis 18.3%. Low birth weight babies (<2500 grams) constituted 55.5% of total neonatal mortality. Conclusion: Early neonatal mortality constitutes an overwhelming proportion of neonatal mortality in Southern Nigeria. This can be significantly curtailed by reducing the incidence and death from prematurity, severe birth asphyxia and neonatal sepsis.