Purpose Adverse events (AEs) assessment by clinicians is a standard practice in a clinical setting. However, studies have found clinicians tend to report fewer AEs, especially subjective AEs. We aimed to explore the difference of subjective AEs assessment between clinicians and patients based on PRO-CTCAE, and to discuss the necessity of incorporating patient into the evaluation of AEs. Methods Between April and July 2019, two different questionnaires with the same subjective AEs were given to patients and clinicians in the Day Chemotherapy ward of Breast Center in the Fourth Hospital of HeBei Medical University. Patients completed a Simplified Chinese version of PRO-CTCAE, including six common subjective AEs of chemotherapy: nausea, vomiting, diarrhea, fatigue, pain, and constipation. Clinicians completed the common terminology criteria for adverse events (CTCAE) with the same AEs. General information of enrolled patients and results from the questionnaires were collected and analyzed. Results 384 paired questionnaires were collected. Clinicians reported less subjective AEs than patients, and the general agreement between patients and clinicians was poor. When considering the grade difference, we utilize weighted kappa coefficient to analysis, and agreement between patients and clinicians was poor (k < 0.4) regardless of the frequency, the severity and interfering with daily life of AEs, and the most discrepancies were within one point. Patients tended to grade severer than the clinician. Conclusions The results of this study showed that there were differences between clinicians and patients in subjective adverse events evaluation. Patient reporting of symptoms can be used as a supplementary method to incorporate the current approach to monitor subjective AEs, to improve the timeliness and accuracy of clinical evaluation of subjective AEs.