BACKGROUND/PURPOSE Selected chemotherapeutic agents used for the treatment of cancer are known to cause skin toxicities. One group of agents, epidermal growth factor receptor (EGFR) inhibitors, characteristically precipitates an acneform rash. Currently, no standard of care exists for the management of the rash resulting from EGFR inhibitors. In order to objectively evaluate any management strategy, a method to quantify the rash is required. The purpose of this paper is to describe a method to quantify the erythema of a facial rash through the use of digital photography and image analysis. METHODS A Canfield OMNIA System using a Canon PowerShot Pro1 camera was used to obtain high-resolution digital images of facial rashes. Digital images were recorded in Joint Photographic Experts Group format, corrected for brightness and white balance and color. A method was developed to analyze digital images of erythema independent of the range of skin pigmentation. RESULTS Two examples are given to illustrate the method developed and its utility. CONCLUSION An inexpensive and portable method is described for objectively monitoring the development of facial erythema in subjects of the full range of skin pigmentation. This method can be used clinically to examine the development and resolution of facial rash erythema in response to treatment.