Guidewire retention is a rare complication of central venous catheter placement, and has been related to operator fatigue, inexperience, and inattention, and inadequate supervision of trainees. The true incidence of guidewire loss after intraoperative placement of central venous catheters is unknown. We report 4 cases of guidewire loss after central venous access procedures performed by anesthesia providers in the operating room. Worsening of patients' clinical condition during catheter placement and complex procedures necessitating more than one guidewire insertion are recurring scenarios in cases involving guidewire loss. Over 6 years at our institution, intraoperative wire loss occurred at a rate of 1:3291 procedures (95% confidence interval of 1/10,000 to 8/10,000).