Objective: To investigate the perception of the prevalence of mental diseases in breast cancer patients and the therapeutic approach to depression undertaken by oncologists. Method: Self-reported questionnaires were sent to 352 breast cancer specialists. The survey contains 11 categories to elicit the perception and identification of mental illnesses in patients, diagnostic procedure, and details of antidepressant prescribed. Logistic regression was used to explore the association of oncologists' characteristics and management of depression in breast cancer patients. Results: Survey response rate was 31.3%. Ninety percent of the oncologists perceived the prevalence of depression to be less than 20%, while half believed that the proportion was less than 5%. The most commonly-used medication for the treatment of depression was BZDs (41.5% [n=39]), followed by Selective Serotonin Reuptake Inhibitors (SSRIs) (30.9% [n=29]). Benzodiazepines (BZDs) were most frequently prescribed (41.5%) despite its known ineligible dependency, followed by Selective Serotonin Reuptake Inhibitors (SSRIs) (30.9%). Choice of BZDs was significantly associated with the career length of oncologists (Odds Ratio [OR]=8.20), and safety of drug (OR=5.57). Contrarily, prescription of SSRIs was associated with efficiency of drug (OR=7.07). Conclusion: Relative to anxiety and insomnia, a lower awareness regarding depression was common among study oncologists. In addition, the quality of care varied among these oncologists. It is necessary to improve both the awareness and management of mental illnesses in order to enhance the total clinical care of breast cancer patients.