The purpose of this study was to investigate the determinants of high neonatal mortality rates in Migori County, Kenya. The neonatal mortality cases were utilised as the target population to the study. A quantitative, descriptive, cross-sectional, non-experimental research design was used. A systematic sampling technique was employed to draw a sample of 201 archived neonatal cases out of 420 neonatal mortality medical records, which constituted the study population. Data were collected by means of a developed questionnaire. The Statistical Package for Social Sciences (SPSS) Version 21 was used to analyse data. The main findings revealed the leading determinants of neonatal mortality were early neonatal period, prematurity, poor 1st Apgar score, low birth weight and neonates with intrapartum complications. Obstetrical haemorrhage and HIV were the main maternal complications associated to neonatal mortalities, while the leading direct causes of death in this study were birth asphyxia and sepsis. Other determinants were gender, rural residence, lowly educated and informally employed mothers. To reduce mortalities, a multifaceted approach is needed to establish quality improvement in neonatal intensive care, reduce preterm birth incidences, and empower mothers socio-economically. / Health Studies / M.A. (Nursing Science)