Background: Empathy is a cornerstone of effective communication. However, clinicians' and patients' perceptions of clinician-expressed empathy might differ. The independent perceptions of patients and clinicians on clinician-expressed empathy in advanced cancer consultations and the associations of these perceptions with patient outcomes are unknown. Objective: We assessed (1) patients' and clinicians' independent perceptions of clinician-(self-)expressed empathy in advanced cancer consultations and (2) the associations between these perceptions and affective patient outcomes. Methods: This observational study included data from 41 consultations in the advanced breast cancer setting. Postconsultation, patients' and clinicians' perceptions of clinician-expressed empathy were assessed, as well as patients' (1) pre-post anxiety, (2) post-anxiety, (3) emotional well-being, and (4) satisfaction. Multilevel regression analyses were run to draw conclusions. Results: Patients perceived higher levels of empathy than clinicians, without a significant relationship between the two (mean [M] = 85.47, standard deviation [SD] = 14.00 vs. M = 61.88, SD = 15.30, 0-100 scale; b = 0.14, p < 0.138, 95% confidence interval [CI] = À0.04 to 0.32). Higher patient-perceived empathy was associated with decreased anxiety [(1) b = À0.67, p = 0.039, 95% CI = À1.30 to À0.03; (2) b = À0.15, p = 0.042, 95% CI = À0.30 to À0.01], higher satisfaction (b = 0.05, p < 0.001, 95% CI = 0.03 to 0.08), and lower emotional distress (b = À0.32, p < 0.001, 95% CI = À0.48 to À0.16). There were no associations with clinicians' perceptions [(1) b = À0.34, p = 0.307, 95% CI = À1.00 to 0.31; (2) b = À0.02, p = 0.824, 95% CI = À0.17 to 0.14; (3) b < 0.01, p = 0.918, 95% CI = À0.03 to 0.02; (4) b = 0.08, p = 0.335, 95% CI = À0.08 to 0.25]. Conclusions: Patients' and clinicians' empathy perceptions differed. In improving patient outcomes, the focus should be on patients' perceptions of clinician-expressed empathy. Future research could focus on ways to elicit patients' perceptions of empathy with the higher aim of improving patient outcomes.