Background: Worldwide it was estimated that 1.5 million pregnant women were living with HIV in 2014 and 2.6 million children under age of 15 years. The majority of the infections are from low and middle income countries and particularly those of the sub Saharan regions. Programs to prevent the vertical transmission of HIV (from mothers to children) can reduce rates of transmission by 92–99% and without interventions the transmission rate of mother to child during pregnancy, delivery and breast feeding can be as high as 45% . Aim of study: To determine the proportion at first DBS test, incidence rate and risk factors associated with HIV infection in exposed infants in Dar es Salaam from 2013 to 2015. Methodology: The study will be a retrospective cohort that will follow up HIV exposed infants until they develop the outcome of interest (HIV infection).The study will be an 18 months follow up of children enrolled into CTC/ART clinics from January 2013 to December 2015 in Dar es Salaam. Data will be extracted from the PMTCT national database. Information from maternal CTC2 and exposed infant cards entered into the health facility and to district database will form the source of data in the PMTCT national database. Mother-child pairs will be linked. Data will be analysed using Stata version 13.0 College Station, Texas 77845 USA. Descriptive statistics will be done using frequencies and percentages. For continuous variables measures of central tendencies such as mean, median and their measure of dispersion will be calculated. Overall incidence rate and variation over follow up will be assessed. Crude and adjusted regression analysis will be done using cox regression. 95% confidence interval and P values of less than 5% will be used to assess the significance of the model.