Background: In the wake of burgeoning slum population, a substantial reduction in the prevalence of diarrhea and acute respiratory infections (ARI) is necessary for to achieve necessary reduction in child mortality in urban India. To achieve this, we need evidence based public health interventions and programs. However, a review of previous studies indicate that national level studies focused on slum population are very few. Therefore, the present study aims to study differentials and determinants of diarrhea and ARI in urban slums of India. Methodology: Using data obtained from the third round of National Family Health Survey conducted in 2005-06, we analyzed information on 2687 under-5 children living in urban slums located in eight selected India cities. Apart from bivariate analysis, logistic regression analysis was performed to identify factor associated with diarrhea and ARI among slum children. Results: The prevalence diarrhea and ARI is about 8% and 8.5%, respectively. Age, birth weight, access to safe water and improved toilet and region emerge as main factors affecting prevalence of diarrhea among slum children. Safe drinking water reduces the likelihood of getting diarrhea by about 19% compared to unsafe water [CI=0.563-1.151]. Children with normal birth are about 51% less likely to suffer from diarrhea compared to those with unknown birth weight [CI=0.368-0.814]. Older children are about 63% less likely to suffer from diarrhea [CI=0.274-0.502]. Children from Southern cities are about half as likely to have diarrhea as children from slums in Northern cities. ARI is associated with age, birth weight, religion, caste, education, family type, safe water, improved toilet, mass-media exposure, region and separate kitchen. Older children and children with normal birth weight are less likely to suffer from ARI. Children from ‘Other’ religions and OBC are 39% [CI=1.000-1.924] and 49% [CI=1.008-2.190], respectively, more likely to suffer from ARI. Parents’ education is strongly associated with prevalence of ARI. Exposure to mass media reduces the likelihood of ARI to 50% compared to the situation when mother of the child did not have any exposure to mass-media [CI=0.324-0.819]. Non-flush toilet and lack of separate kitchen increase the likelihood of ARI. Children from slums located in Southern region are less likely to suffer from ARI. Conclusion: The findings call for dedicated programs and policies, in line with those already existing ones such as RAY, IHSDP, NUHM, ICDS and JNNURM, for the development of urban slums through provision of affordable housing, improved sanitation, safe water and clean fuel. Adequate nutrition to mothers and their children should be ensured and vulnerable groups identified in the analysis should be the focus of future public health intervention and strategies. The use of mass-media to change health behavior should also be considered.