We were able to calculate the frequency of inadvertent vein or peripheral nerve biopsy from 1 other report.2 In that study, 4 of 250 consecutive biopsies (1.6%) were of either a nerve or vein rather than an artery, a result that fell within our 95% confidence interval. These estimates provide physicians with some guidelines on how to inform patients of the risk of repeat biopsy. Given the inconvenience, potential morbidity, cost of repeat temporal artery biopsy, and delay in obtaining a final diagnosis, efforts should be made to reduce the frequency of inadvertent biopsy as much as possible. The principle reason for inadvertent biopsy is unclear but may include lack of surgical experience or inadequate visualization of the tissue at the time of removal. Reducing inadvertent biopsies can be achieved first by raising awareness of the phenomenon and then by including a standardized procedure to confirm the correct tissue at the time of harvest. One method could use a magnifying lens (≥5×) to inspect the cut ends of the putative artery immediately after excision. These inexpensive lenses, which can be sterilized and packaged for use during surgery, have magnification sufficient to aid in the distinction of an artery of this caliber from a vein or nerve.