Abstract : A vaccine is a biological preparation that enhances immunity to a certain illness. It often comprises an agent that mimics the pathogenic bacterium and is frequently manufactured from attenuated or dead versions of the microbe, its toxins, or one of its surface proteins. Studying the prevalence and reasons for incomplete vaccination. Identifying factors that contributed to the missed opportunities for vaccination among children less than two years of age in Baghdad city Karkh region at PHCCs level. A descriptive, cross-sectional study with an analytic element. Collection of data was carried out during period from the beginning of March, till end of July 2020. The total number of the studied children were 820; of these 400 (48.8%) were males, and 420 (51.2%) were females, the male to female ratio was 0.95:1 and the mean age (±SD) was 9 (±5) months, (range 1-24 months). It was found that (77.7%) of the children were completely vaccinated, and (22.3%) were incompletely vaccinated. The study found a significant statistical associations between vaccination status and mother`s education (P=<0.001). There is no completely non vaccinated children observed in this study. One in every four children was found to be incompletely vaccinated. Male children have higher proportion of incomplete vaccination. Mother and father educational level affect the vaccination status of their children. More than two thirds of the incompletely vaccinated children live in extended families. More than one third of the incompletely vaccinated children have history of multiple delayed vaccination times.