There are four diagnostic methods: Inspection, auscultation and olfaction, inquiry or interrogation, and pulse-taking and palpation.
| (a) | Inspection (looking): observes patient vitality, complexion, mental state and faculty; and examines physical signs — tongue manifestation, and body secretions and excretions. | |
| (b) | Auscultation and olfaction (listening and smelling): gathers information from body sounds — voice, cough, breathing quality, and scent (body odors or abnormal smells). | |
| (c) | Interrogation (inquiry): interviews the patient regarding the disease cause and the patient’s suffering — chills, fever, sweating, pain, taste, stools, and urine — or associated factors to determine the state of health, major problems, and illness progress and duration. | |
| (d) | Pulse-taking and palpation (feeling and touching): interprets the patient’s pulse to understand the disease condition; and touches and presses body parts, such as the head, chest, abdomen, limbs, and skin, to identify abnormal conditions. |
The Basic Questions says, “Knowing the disease by observation is miraculous; knowing by auscultation and olfaction is sage; knowing by interrogation is skillful; and knowing by pulse-taking and palpation is ingenious.” The four diagnostic methods are integral because they differentiate syndromes 
and direct treatment.
TCM suggests, “The condition of the interior is inevitably reflected on the exterior.” Correct differentiation of syndromes 
relies on external manifestations to determine the physiological state and pathological changes of Yin and Yang, Qi and blood, the Zang–Fu organs, meridians, and collaterals.