As stated above the Health Belief Model by itself has been found wanting in terms of being able to explain parents' behaviour with respect to immunising their children. Conceptual pieces have been written describing how subjective risk perception and risky decision-making theories may be useful in understanding parents' behaviour and choices although these have not drawn on primary data [7] . Using a qualitative design, the aim of this study was to: explore the salience of the decision-making and risk perception findings to parents' choices to immunise their young children; examine the utility of the risk perception and decision-making theories to provide a more detailed explanation of the differences between immunisers' and nonimmunisers' perceptions of severity, susceptibility to disease and benefits of vaccines; and understand how these theories might explain perceptions of risk and reactions to a 'new strain of flu' for themselves and their children.