Objective: Immune checkpoint inhibitor-related pneumonitis (ICI-P), as a rare, immune-related adverse event, is difficult to diagnose and treat for clinicians because of its life-threatening adverse events and nonspecific clinical and laboratory findings. Material and Methods: Patients with newly developed pulmonary infiltrates receiving ICI for cancer treatment were included in this study, and their images were re-evaluated by a radiologist. Results: In this study, 32 (88.9%) male and four (11.3%) female patients with a median age of 62 years (range: 20-70 years) were enrolled, of whom 26 patients (72.3%) were diagnosed with non-small cell lung cancer. The most frequent ICI-P-related symptom was cough (63.9%). The median time to the occurrence of ICI-P was 3.5 months (range: 0.3-20 months), and the median number of cycles was four (range: 1-25). Ten patients needed hospitalization, 13 patients were found with permanent termination of ICI therapy, and ICI-P recurred in six patients (16.7%). Other immunosuppressive treatments, such as using mycophenolate mofetil and infliximab, were required in three steroid-refractory patients. No patient died due to uncontrolled ICI-P. Conclusion: In our study, consolidation was the most common radiological finding of ICI-P, which may involve the contralateral side as well as the tumor margin, possibly mimicking lymphangitic spread. Although ICI-P diagnosis is based on the exclusion of other differential diagnoses, it can mimic many other clinical conditions. Empirical use of steroids should not be avoided if there is clinical suspicion because of the risk of mortality.