Through the efforts of the global campaign to eradicate poliomyelitis, polio cases have declined worldwide, from 35,251 cases in 1988, to 1449 cases as of 28 October 2005. However, confirmed cases of wild polio virus continue to be reported from Northern Nigeria. This paper examines the reasons for the difficulties in eradicating polio in Northern Nigeria from the perspective of residents of one town, Zaria, in northern Kaduna State. Research methods included participant observation, open-ended interviews and the collection of polio-related documents. While some people believed that the vaccine was contaminated by anti-fertility substances, others questioned the focus on polio when measles and malaria were considered more harmful. Some also distrusted claims about the safety of Western biomedicine. These concerns relate to questions about the appropriateness of vertical health interventions, where levels of routine immunization are low. While the Polio Eradication Initiative was considered to be cost-effective by Western donors, from the perspective of some people in Zaria it was seen as undermining primary health care, suggesting that a collaborative, community-based framework for primary health care, which includes routine immunization, would be a more acceptable approach.