This case study presents the inadvertent catheterization of a traumatic hemopneumothorax. A 22-year-old man sustained multiple stab wounds, including the left chest with a resultant hemopneumothorax. Upon arrival at a Level 1 trauma center, an ipsilateral subclavian central catheter was placed, blood was freely aspirated, and because of the patient's critical status, immediately utilized for resuscitation prior to line verification by radiography. A short time later, the catheter was felt to be malpositioned, most likely in the left intrathoracic space, and removed. The patient subsequently recovered and was discharged home 3 days later.