Nurses are increasingly working more autonomously in extended roles, yet we know little about the nature of the decisions they make. Decisions vary in terms of complexity, ambiguity and presentation, and the nature of the decision task impacts on the process of decision making, such as the likelihood of using a decision tool. Thus, knowledge about the nature of nursing decisions is essential for development of effective decision tools. This article presents an analysis of 410 nurse—patient consultations and interviews with 76 primary care nurses, and explores the nature of the decisions that primary care nurses make and the impact of that on their use of and attitudes towards decision tools.