More children in Ethiopia start and do not complete all expanded programme on immunizationrn(EPI) recommended for routine immunization (RI) vaccines than those who complete their vaccinernschedule. This group of defaulter is bigger than the group that has no vaccines. However, bothrngroups of children that have no vaccines and those that have partial vaccination are in similar riskrnof acquiring vaccine preventable diseases. This study aims to assess demographic, socio economic,rnenvironmental and health service factors affecting childhood vaccination incompletion, and torndetermine the extent of incomplete vaccination within and between regions in Ethiopia based onrnEDHS 2011 data. In this study a total of 6797 children 12 to 59 months of age were included (meanrnage of 36 and standard deviation 13.655 months). Among these children 33.76% were completelyrnimmunized while 66.24% were partially vaccinated. Descriptive data analyses, binary logistic, andrnmultilevel logistic regression analyses were used. This study identified that region, wealth index, sexrnof household head, birth order of a child, being of wise of a mother to have balanced family life,rnfrequency of a mother listening to radio, and mothers’ getting of prenatal care and assistant from arnhealth professional were statistically significant at 5% level for a child 12 to 59 month of age beingrnpartially immunized. The multilevel logistic regression analysis revealed that there wasrnheterogeneity across regions. Between regional variations for vaccination incompletion of childrenrn12 to 59 months of age was 1.0596 with standard error 0.4603. Intraclass correlation between twornindividual mothers in the same region was 0.322067. A low ICC indicates relatively small betweenrnregional variations, but in this study it was high. Region Tigray, Afar, Oromia, Somali (at 10%rnsignificance level), Gambela, Addis Ababa and Dire Dawa were statistically significant regions forrnthe variation of children vaccination defaulting in the country. The chance of a child 12 to 59 monthrnof age being partially immunized was 67% on average in the country. The average probability of arnchild 12 to 59 months of age being under vaccinated was below the average (0.6661) in Tigrayrn(0.3747), Addis Abeba (0.1773) and DireDawa (0.4596) while it was higher in Afar (0.8997),rnOromia (0.7969), Somali (0.7809), and Gamble (0.8310) regions