This paper surveys the contributions and applications of queuing theory in the field of healthcare. The paper summarizes a range of queuing theory results in the following areas: waiting time and utilization analysis, system design, and appointment systems. The paper also considers results for systems at different scales, including individual departments (or units), healthcare facilities, and regional healthcare systems. The goal is to provide sufficient information to analysts who are interested in using queuing theory to model a healthcare process and want to locate the details of relevant models. Description: This paper has been submitted for publication in IIE Transactions.