The aim of this study was to elucidate the meaning and dimensions of the concepts uncertain, control, secure and risk. The results from the concept determination were discussed in relation to the phenomenon of women’s health and illness experiences following a myocardial infarction (MI). A method of concept determination was used. The findings disclose the complexity of the women’s existential uncertainty that was experienced by women following an MI. This uncertainty is an important matter in relation to the women’s health processes and to their well-being. In these processes the concepts control, secure and risk play a central role. Western culture of today seems to be characterized by a search for greater safety. Lifestyle disorders, such as an MI, seems to make people more aware of specific risk factors that may be avoided. Women who have suffered an MI want to be as safe as possible in order to not fall ill again, but live well. The women’s ambition to achieve greater safety may lead them to feel even greater uncertainty. It is a challenging act for healthcare professionals to balance their support, to give information and to care for patients with acute coronary syndromes.