Background There is a growing interest in the use of targeted and immunotherapies in oncology. However, the assessment of side effects can be different due to interpretation of patients' health status by healthcare professionals in oncology outpatient clinics. Objective To demonstrate the differences in the assessments of side effects conducted independently by a clinical pharmacist and nurses in patients who receive targeted therapies at an oncology outpatient clinic. Setting The study was conducted at the University Oncology Hospital in an outpatient clinic from October 2015 to March 2016. Method Patients receiving ipilimumab, nivolumab, pembrolizumab, bevacizumab, panitumumab or cetuximab during study period were included. The assessment of side effects was conducted by a pharmacist and nurse independently using the NCI-CTCAE version-2. Main outcome measure To compare the severity assessments of side effects between a clinical pharmacist and nurses in an outpatient clinic. Results During the study, 204 visits for 43 patients with a total of 5508 side effect assessments were recorded where 1137 (20.64%) assessments were graded differently. Out of 1137 assessments, 473 of them were graded higher by a clinical pharmacist whereas 664 were graded higher by nurses. Statistically significant differences were detected in the assessment of vomiting, taste changes, sense changes, alopecia, fatigue, mood changes, anxiety, hearing impairment, and allergic reactions. Conclusion An assessment of side effects by healthcare providers in patients with cancer may be challenging due to an increased workload in clinics and undistinguishable symptoms of side effects and cancer itself. Therefore, a new care model which increases an interprofessional communication may improve pharmaceutical care in oncology outpatient clinics.