Almost all modern medical care is delivered in the setting of many overlapping systems. Each system may consist of multiple providers and in most cases electronic and mechanical components. Even "simple" outpatient care is delivered by teams of providers, administrators, and devices. Critically ill inpatients are cared for in extraordinarily complex systems with hundreds of human and non-human elements. The science of complex systems has exploded in recent decades, and there is a large body of knowledge about how such systems function effectively or ineffectively. Many principles of systems science are simple to understand and apply, but few Otolaryngologists are well educated about them. A basic knowledge of systems science will greatly improve the Otolaryngologist's ability to function in complex health care systems and to provide the best care for his or her patients.