Endobronchial ultrasound-guided transbronchial fine needle aspiration (EBUS-TBNA) has become an important tool in the diagnosis and staging of malignant tumors of the lungs and mediastinum. Rapid on-site evaluation (ROSE) denotes a cytomorphological diagnostic procedure that allows assessment of the adequacy and accuracy of the material obtained during bronchoscopy within a few minutes in or near the bronchoscopy suite (on-site) using a quick staining of smears. This results in a significant decrease in the number of repeated bronchoscopy procedures required to recover an adequate biopsy sample and is therefore both time and cost effective. The obtained material can be further assessed as conventional cytological specimens or alternatively using the thin-prep technique for definitive cytopathology diagnosis and/or embedded in paraffin for immunohistochemical or molecular analyses such as DNA sequencing or flow cytometry.