A True experimental pretest posttest study was conducted to assess the factors influencing the utilization and non- utilization of under five immunization services and to evaluate the effectiveness of guided health action on utilization of immunization services among parents of under five children in a selected area of Dehradun, Uttarakhand. The research hypothesis stated that the guided health action would significantly increase the utilization of immunization services in the experimental group and was test at (p<0.05). Total 120 children who met the selection criteria were selected using convenient sampling and were divided into experimental group (60) and control group (60). Pre interventional immunization status was assessed along with the reasons of not utilizing immunization services using a structured immunization checklist and structured questionnaire respectively in both the groups. Guided health action was given to the experimental group through a combination of SMS, phone calls and personal contacts followed by post intervention data collection. The results showed significant reduction in the missed vaccination doses in experimental group after intervention (43) as compared to the missed doses before intervention (142) (2 = 28.47, p value <0.05). The major reasons reported by the parents for not immunizing their children were illness of the child and unawareness regarding need to return for 2nd and 3rd dose of immunization. The least reported reason was no faith in immunization. The findings of the present study revealed that the guided health action was effective in improving the utilization of under-five immunization status.