Surgical site marking is an important safety procedure prior to surgery. Visibility of pen marks is affected by surgical wash which increases the risk of wrong-site surgery. Additionally, multiple patient contact with a single pen is a potential source of bacterial transmission. In this study we compare pens commonly used for surgical marking in Australia. We conducted an unblinded, prospective cohort study comparing 12 marking pens. Six volunteers' thighs were marked with each pen. Standardized photographs were taken before and after wash with four prep solutions. Ink visibility was analysed using grayscale images, comparing the pen mark tone before and after wash. The pen tips were swabbed for culture. Red tinted 2% chlorhexidine gluconate (w/v) with 70% isopropyl alcohol (v/v) was shown to reduce pen mark visibility significantly more than the other solutions used. The Pentel N50 permanent marker and Aspen WriteSite Plus were least affected by wash. No pen tip cultured any bacteria. When marking the correct site for surgery, we recommend the use of either the Pentel N50 permanent marker or Aspen Writesite Plus pen. A 2-min interval between patient contact limits bacterial transmission. © 2019 Royal Australasian College of Surgeons.