Purpose : To evaluate effectiveness of oblique approach under biplane fluoroscopic guidance in transthoracicfine needle aspiration biopsy. Materials and Methods : Fourteen consecutive patients underwent transthoracic fineneedle aspiration biopsy for subcarinal lesions. Subcarina was the only accessible biopsy site in 13 patients.Subcarinal biopsy was performed to determine the presence of metastasis in an enlarged subcarinal lymph node inthe remaning one patient. Before biopsy we evaluated the size and location of the lesion on preliminary plainchest X-ray film and CT scan. Under dual projection fluoroscopic guidence, biopsy was performed through rightposterior intercostal space with the patient prone by using oblique approach. On 15 degree LAO projection theneedle was directed to the area anterior to the spine and advanced to the line extending through the posteriorwall of the main bronchus. Results : Cytologic diagnosis was made in 12 out of 14 patients(accuracy 85.7%). Thefinal diagnosis consisted of 5 squamous cell carcinoma, 5 small cell carcinoma, 1 adenocarcinoma and 1adenosquamous carcinoma. Pneumothorax developed in 2 patients(14%) and was managed by chest tube drainage. Mildhemoptysis were observed in 2. Conclusion : Transthoracic fine needle aspiration biopsy using oblique approachunder biplane fluoroscopic guidance is a relatively safe and sensitive method for the histologic diagnosis ofsubcarinal lesion.