Transthoracic Needle Aspiration (TTNA) for diagnosing thoracic lesions are usually performed with image guidance, including thoracic computed tomography scan and thoracic ultrasound. The aim of this study is to describe the characteristics of samples, and diagnostic accuracy of TTNA using US guidance compare to CT guidance. Image-guided TTNA were performed in 91 consecutive patients suspected of lung cancer on clinically and radiological work-up. Image guidance was selected randomly. The final diagnosis was based on cytology analysis or clinical follow-up. For thoracic ultrasound guided TTNA, the accuracy, sensitivity, specificity, were 87.8%, 91.6%, and 77.7%, respectively. For thoracic CT- guided TTNA the accuracy, sensitivity, specificity, were 86.84%, 78.3%, and 100%. Thoracic US-guided TTNA had a high sensitivity and specificity in lesions that abut the chest wall.