Background: Child vaccination is perhaps the first line of defense to ensure a healthy society. Unfortunately, the coverage of child vaccination in Pakistan is poor resulting in unnecessary yet preventable deaths. This study investigated the determinants and reasons for not vaccinating children in Pakistan. Materials and Methods: The study used the Pakistan Integrated Household Survey/Household Integrated Economic Survey 2001-2002 data. Demographic, distance to health facility, poverty status, literacy and education, and location of residence were used as determinants of nonimmunization of children. Descriptive statistics including frequency distribution, proportions for categorical variables and mean for continuous variables, and logistic regression analysis were done using the Stata 11.0. Results: Almost 7.73% children in Pakistan were never immunized. More than 87.4% of these lived in the rural areas. Prevalence of nonimmunization was highest in Balochistan compared to other provinces. Large households appeared to have increased risk of a child not being vaccinated. Moreover, low literacy and education of the head of the household and the spouse was also associated with low vaccination coverage. Distance from the health facility was found to be another factor related to nonimmunization of children. Increase in per capita income significantly decreased the risk of missing vaccinations. Conclusions: Prevention and immunization programs should focus more on high-risk regions such as Balochistan and rural areas. Literacy, education, and economic status were among the other significant factors associated with low vaccination rates, which need a special focus in the public policy to achieve the target of a healthy society.