BACKGROUND: Anxiety and depression are prevalent in women with breast cancer. These can affect their autonomic nervous system and hemodynamic stability, which are important factors during operation. We aimed to assess the effect of anxiety and depression on heart rate variability (HRV) in patients with breast cancer. METHODS: Forty-nine women with breast cancer, scheduled for surgery, were asked to complete depression and anxiety questionnaires and categorized into depressed/non-depressed and anxious/non-anxious groups. Their electrocardiography (EKG) were assessed for 150 s on admission, before, and after induction of anesthesia for the presence, frequency, and range of HRV. Patients\' blood pressure (BP) and HR were recorded, and normal unit high frequency (nuHF), normal unit low frequency (nuLF), LF/HF ratio, HRV index, and systolic and diastolic BP were compared between the groups in three intervals. RESULTS: Anxious and depressed groups had a significantly higher systolic, diastolic, and mean BP before and after induction and higher nuLF before induction, while the changes in nuLF, LF/HF ratio, and HRV index were not significant. Both groups with and without mood disorders had increased BP and HR before induction, which decreased after induction (P < 0.001). Decreased mean BP after induction was associated with anxiety (P < 0.05). CONCLUSION: According to the results of this study, patients with depression had less HRV in the operating theater, than the non-depressed group. After induction of anesthesia, the decrease in BP was associated with anxiety, while BP of the depressed group was higher than the non-depressed group at all intervals.