Introduction–Incomplete immunization among under five children is one of the major public health problems in India. Objectives– To explore the reasons behind incomplete immunization among under five children. Material & methods– It was a qualitative study conducted during May 2017–Oct.2017(6 months). In–depth interviews and Focus group discussions (FGDs) were conducted among parents of unimmunized and partially immunized children and healthcare workers (ASHAs and AWWs). Study tool was semi–structured interview guide. Analysis was done using thematic analysis. Ethical clearance and informed consent was obtained before conducting the study. Results– A total of 15 in depth interviews (8 mothers,1 father and 6 key informants) and two FGDs were conducted. Major key areas came out to be lack of knowledge regarding benefits of immunization, side –effects due to immunization, rumors and fake videos, resistance from husband & in–laws, migration of mothers and loss of immunization card. Conclusion– There is an urgent need of awareness regarding benefits, possible side effects and contraindications of immunization.