Skin preparation solutions are used to clean the skin of the patient before surgery to decrease the rate if infection. This is particularly important for hip replacement to reduce the risk of prosthetic joint infection. The use of a mark on the skin for site identification has become the standard of care to decrease wrong site surgery. The Joint Commission has mandated site identification as part of the surgical "time-out". This procedure is also mandated by hospital policy. Preliminary work on cadaveric skin shows that the type of skin preparation can erase the mark used for surgical site identification. Erasure of the mark presents the surgeon with difficulty in performing the site identification. Any error or lack of visualization of the site marking could lead to catastrophic wrong site surgery. Our hypothesis is that chlorhexidine based skin preparation solutions erase site marking in comparison to iodine based skin marking solutions. We intend to prospectively study twenty patients undergoing total hip arthroplasty to determine if the site marking is erased by chlorhexidine based skin preparation solutions when compared to iodine based skin preparation solutions. This information is critical to all surgeons who must balance the risk of wound infection versus wrong site surgery.