Patients with medically unexplained symptoms (MUS) have little or no demonstrable disease explanation for the symptoms, and comorbid psychiatric disorders are frequent. Although common, costly, distressed, and often receiving ill-advised testing and treatments, most MUS patients go unrecognized, which precludes effective treatment. To enhance recognition, we present an emerging perspective that envisions a unitary classification for the entire spectrum of MUS where this diagnosis comprises severity, duration, and comorbidity. We then present a specific approach for making the diagnosis at each level of severity. Although our disease-based diagnosis system dictates excluding organic disease to diagnose MUS, much exclusion can occur clinically without recourse to laboratory or consultative evaluation because the majority of patients are mild. Only the less common, "difficult" patients with moderate and severe MUS require investigation to exclude organic diseases. By explicitly diagnosing and labeling all severity levels of MUS, we propose that this diagnostic approach cannot only facilitate effective treatment but also reduce the cost and morbidity from unnecessary interventions.