This paper examines utilization of immunization services available to the children in slums in Mumbai. The present study is based on the primary data, collected using cluster sampling of sample size of 433 reproductive women who have given at least one live birth prior to the survey. The SLI was constructed from household amenities like, housing quality, drinking water sources, electricity and toilet facilities. The findings revealed a shocking low level of vaccination among the children of 12-23 months old from the Rafi Nagar slum. Primary vaccination was just 48 percent. Even Logistic regression reveals that the children from low SLI category and of illiterate women were not availing themselves of child care services. Thus this paper suggests that the measles vaccination programme has to focus not only its coverage but also its timing to include awareness about immunization programmes especially among the illiterate women.