Background: Immunization is a reliable evidence-based approach to eradicate deadly infectious diseases. National family health survey (NHFS4) data reveals that immunization after 1 year of age dropped in Kanyakumari district, Tamil Nadu, India. Methods: Our aim was to determine immunization status and reasons for partial or non-immunization of children aged 1 to 5 years in Kanyakumari district from April 2019 to March 2020. It’s a prospective and descriptive hospital-based study. Here 613 children were split-up in three categories based on ministry of health and family welfare (MOHFW) guidelines as fully, partially or unimmunized. The samples were analysed with IBM. SPSS statistics software 23.0 Version.Results: Of the 613 children 5 were excluded from the study due to contraindications to immunizations. Of the 608 children 529 (87%) were fully immunized, 79(13%) were partially immunized and none were unimmunized. Among partially immunized, 2 parents lacked information (2.5%), 26 parents lacked motivation (32.9%), 45 parents faced obstacles (57%) and 6 parents had other reasons (7.6%). 2 parents who lacked information were migrant laborers, illiterates and the children were home delivered. In the partial immunization, chi-square and regression analysis revealed that for female gender the p-value was 0.001, OR 2.084 with 95% confidence interval (CI) (1.347 to 3.226), for parental education the p-value was 0.0005, OR 1.561 with 95% CI (1.034 to 2.335) and for home delivery the p value was 0.0005, OR 1.564 with 95% CI (1.006 to 2.432). Conclusions: The study determines that factors associated with partial immunization are female children, illiterate/less educated parents and home delivery.