Immunisation has been a proven and one of the mostcost-effective child survival interventions in the world.1Every country has its own immunisation programmeto provide selected vaccines to the targeted group ofpopulation, generally focusing on infants and children,and pregnant women, who are at a high risk of diseasespreventable by vaccines. There are at least 27 causativeagents against which vaccines are available and manymore agents are targeted for development of vaccines.2The number of antigens used in the immunisationprogrammes varies from country to country. However,there are a few selected antigens which are given againstdiphtheria, pertussis, tetanus, poliomyelitis, measles andhepatitis B which are part of immunisation programmesin most of the countries in the world. The first vaccine,against small pox, was discovered in 1798, and fromthe early 18th century, the British health administrationintroduced vaccination against small pox in the Indiansub-continent.3 The first doses of smallpox vaccinelymph in India arrived in May 1802.4 The most strikingsuccess of these efforts has been the eradication ofsmallpox disease from the world.5 EPI is implemented in192 countries of the world. But data shows that despitebeing a proven cost-effective preventive public healthintervention, the benefits of immunisation is not reachingmany children who are at risk of the diseases preventableby these vaccines. Majority of the children who do notreceive these vaccines live in the developing countries. Itis important to understand the underlying factors whichcauses non-immunisation of children and specifically, inBangladesh, in this review article.