The combination chemotherapy of irinotecan with 5-fluorouracil and leucovorin (FOLFIRI regimen) was recently proven to be beneficial in patients with advanced colorectal cancer. Pulmonary toxicity is very rare in adverse effects of irinotecan. No case of organizing pneumonia (also known as bronchiolitis obliterans organizing pneumonia) associated with FOLFIRI chemotherapy has been reported. We experienced a case of a 62-year-old man who presented persistent dry cough and progressive dyspnea after receiving chemotherapy with FOLFIRI regimen. After surgical lung biopsy, the patient was diagnosed with FOLFIRI chemotherapy-induced organizing pneumonia which was successfully treated with steroid therapy.