Background: Meticulous assessment, monitoring, and treatment of symptoms are key components of palliative care. The Symptom Assessment Scale (SAS) is a 0-10 numerical rating scale (NRS) used for self-report of sleep, appetite, nausea, bowels, breathing, fatigue, and pain. Ideally, symptom rating should be by self-report; however, the ratings are often completed by nurses. The aim of this study was to examine the relationship between simultaneous symptom ratings of patients and nurses in an Australian inpatient palliative care unit. Methods: All inpatients and their treating nurse (blinded to the patient's report) scored the SAS weekly. Nurse symptom rating was considered accurate if the score for an individual symptom differed by ≤1. The relationship for each dyad was examined by comparing absolute values, mean differences, and Pearson correlations. Results: Sixty-four pairs of symptom ratings were obtained from 29 patients (mean 65 years, male 55%, malignancy 90%, mean Karnofsky 50). The absolute differences were closest for nausea, bowels, and breathing domains, and worst for appetite. Mean differences and Pearson correlations did not adequately reflect the disparity between patient and nurse symptom rating, and nurses systematically underreported symptoms. The total difference for the seven items ranged from nurses overreporting the patients' symptoms by 39 points to underreporting by 31 out of a possible 70 points. Discussion: Proxy symptom assessment only modestly correlates with patient symptom rating, can significantly misrepresent the patient's actual symptom burden, and should only be used when the patient is absolutely unable to contribute his or her own view.