Background: Patients undergoing chemotherapy experience a wide range of physical and psychological symptoms due to the treatment they receive. The quality of care for these patients is primarily influenced by the caring behaviors of nurses. Objectives: Given that differences in the perception of caring behaviors between patients undergoing chemotherapy and nurses may leave patients' needs unmet, this study was conducted to compare the perceptions of oncology nurses and patients undergoing chemotherapy regarding nurses' caring behaviors. Methods: In this descriptive-comparative study, 97 patients undergoing chemotherapy in the Oncology Departments of Imam Hossein (AS) and Taleghani Hospitals in Tehran were selected through convenience sampling. Sampling was conducted daily from 8 a.m. to 6 p.m. until the required sample size was achieved. A census was performed on 39 nurses working in these hospitals. Data were collected using a demographic information form and the Caring Behavior Inventory. The collected data were analyzed using SPSS 24 and statistical tests, including t-tests, one-way ANOVA, and Spearman's correlation coefficient. Results: Nurses had significantly higher perceptions of the assurance of human presence, respectful deference to others, and positive connectedness subscales than patients (P = 0.007). However, there was no significant difference in the perception level for the knowledge and skill subscale between nurses and patients (P = 0.72). Overall, nurses assigned higher scores to caring behaviors than patients (P = 0.011). The experience of previous hospitalization among patients was significantly associated with their perception of overall caring behaviors (P < 0.001) and all subscales. Among nurses, gender had a positive correlation with their perception of assurance of human presence (P = 0.02) and overall caring behaviors (P = 0.04). Conclusions: Given the differences in how oncology nurses and patients undergoing chemotherapy perceive caring behaviors, it is essential for oncology nurses to incorporate patients' perceptions when prioritizing their caring behaviors and to strive to provide patient-centered care at all times.