OBJECTIVE: Achieving high rates of childhood immunisation is an important public health aim. Currently, however, immunisation uptake in Australia is disappointing. This qualitative study investigated the factors that influence parental decision making for childhood immunisation, and whether parents' experiences were better conceptualised in terms of static subjective expected utility models or in terms of a more dynamic process. METHOD: Semi-structured in-depth interviews were conducted with 20 predominantly middle-class mothers--17 immunizers and three non-immunizers, in Melbourne, Victoria, in 1997. The data were then examined using thematic analysis. RESULTS: The results suggested that for these participants the decision regarding childhood immunization was better conceptualized as a dynamic process. The decision required initial consideration, implementation then maintenance. CONCLUSION: If a better understanding of immunization decision making is to be achieved, future studies must look beyond static frameworks. IMPLICATION: Clearer insight into the dynamic nature of immunization decision making should assist in the identification of more effective methods of promoting childhood immunization to groups at risk of non-compliance.