Previous studies indicate that under-five mortality rates have remained stagnant and Uganda failed to meet the Millennium Development Goals target and hence unlikely to achieve Sustainable Development Goals. Although effective health reforms and programs such as the Immunization Integrated Management of Childhood Illness (IMCI), and Home Based Management of Fever (HBMF) and increasing health expenditure were undertaken since1990s, health outcomes especially under-five mortality rates have remained poor. Uganda’s under-five mortality rate has remained high that is 68 per 1000 live birth in relation to MDGs target 56 per 1000 live birth in 2014 .The MDGs assessment report by United Nation Development Programme (UNDP) shows that the low level of public health expenditure is a major factor determining poor child health outcomes in Uganda. However empirical evidence on the health expenditure and its effect on under-five mortality rate have remained inconclusive. Simple Ordinary least squares (OLS) method was used to investigate the relationship between public health spending and under-five mortality rate. The results revealed that recurrent health expenditure, capital health expenditure, women literacy rate and percentage of population living in urban areas are strongly associated with under-five mortality rate. The study therefore recommends that the government should increase health spending per capita in relation to the increase in population and increase accessibility to education for the girl child.