Developing a care plan for a patient requires an understanding of interactions and dependencies between procedures, and of their possible outcomes for an individual patient, and it requires the planner to keep track of this information as the proposed plan evolves. This is difficult even for experienced clinicians, but increasingly patients are expected (and expect) to participate. We describe an argumentation-based planning support system designed to ameliorate the cognitive load imposed by the planning and communication elements of such tasks. An initial evaluation study in the field of genetic counseling produced promising results. The approach may provide a general aid for clinicians and patients in visualizing, customizing, evaluating and communicating about care plans.