OBJECTIVES: To compare the costs of human and automated follow-up processes in ambulatory care. STUDY DESIGN: Analysis of costs of nurse-initiated and interactive voice response (IVR) system follow-up interventions. METHODS: Using national cost data and data on follow-up processes and outcomes from a previous study, we examined the costs to the healthcare system and providers of developing a follow-up process using nurse-initiated telephone calls compared with calls made by an IVR. RESULTS: Whether using nurse-initiated telephone calls or IVR calls, costs over the first 2 years of follow-up for a practice assumed to have 4800 acute care patient visits per year are approximately the same. After 2 years, IVR follow-up is approximately $9000 per year less expensive than nurse follow-up. In addition, overall cost savings are greater with IVR. CONCLUSIONS: Follow-up of ambulatory care patients is a way to assess risks of future problems and associated costs and to improve quality of care. An automated follow-up process using IVR is more efficient than one based on nurse-initiated follow-up calls.