Thoracic paravertebral block is performed for the treatment of patients with chronic pain, such as complex regional pain syndrome (CRPS) and post-herpetic neuralgia. Thoracic paravertebral block can result in iatrogenic pneumothorax. Because pneumothorax can develop into medical emergencies and needle aspiration or chest tube placement may be needed, early diagnosis is very important. Recently, thoracic ultrasonography has begun to be used to diagnose pneumothorax. In addition, ultrasound-guided aspiration can be an accurate and safe technique for treatment of pneumothorax, as the needle position can be followed in real time. We report a case of iatrogenic pneumothorax following thoracic paravertebral block for the treatment of chronic pain due to CRPS, treated successfully by ultrasound-guided aspiration.