OBJECTIVE: Unmet supportive care needs of patients decrease patient perception of physician empathy (PE). We explored whether the accurate physician understanding of a given patient's unmet needs (AU), could buffer the adverse effect of these unmet needs on PE. METHODS: In a cross-sectional design, 28 physicians and 201 metastatic cancer patients independently assessed the unmet supportive care needs of patients. AU was calculated as the sum of items for which physicians correctly rated the level of patient needs. PE and covariates were assessed using self-reported questionnaires. Multilevel analyses were carried out. RESULTS: AU did not directly affect PE but acted as a moderator. When patients were highly expressive and when physicians perceived poor rapport with the patient, a high AU moderated the adverse effect of patient unmet needs on PE. CONCLUSION: Physician AU has the power to protect the doctor-patient relationship in spite of high patient unmet needs, but only in certain conditions. PRACTICE IMPLICATIONS: Physicians should be encouraged toward AU but warned that high rapport and patient low emotional expression may impede an accurate reading of patients. In this latter case, they should request a formal assessment of their patients' needs.