OBJECTIVES: Immunization dose was considered as a missed immunization dose if pediatric didn’t receive at least one immunization dose. The aims of this study are to determine the frequency and percent of missed doses among pediatric immunization schedule, to determine the number of immunization doses missed by each child, and to evaluate the correlation between missed dose frequency and parent’s knowledge.  METHODS: Data was collected retrospectively from 528 pediatric immunization cards in Iraq to obtain the immunization history of each individual child. This study was restricted the analyses to the vaccines administered before age of 2 years. Each pediatric must received seven doses at seven different times, every dose consist of many types of vaccines. Validated questionnaire was used to measure immunization parent’s knowledge and Spearman rho correlation test was used to evaluate the correlation between missed dose frequency and parent’s knowledge. RESULTS: More than 30% of missed immunization doses were shown in the seventh or last dose (OPV+DTP) at 18 months of age. The majority of pediatrics (54.1%) was immunized without any missed immunization dose out of seven immunization doses. Four pediatrics (0.8%) were only having six missed immunization doses. Missed immunization dose found to be negatively correlated with knowledge score (correlation= -0.263, P-value<0.001). CONCLUSIONS: This study suggests that compliance with WHO immunization recommendations is low and inappropriate immunization doses were occurred frequently, and leading to incomplete or partial immunization compliance. With an increase in parent’s knowledge of immunization guidelines against infectious agents, it is very important to implement strategies that will lead to improved and developed immunization practice and childhood immunization coverage in the future.