An approach to detection of phishing webpages based on visual similarity is proposed, which can be utilized as a part of an enterprise solution for anti-phishing. A legitimate webpage owner can use this approach to search the Web for suspicious webpages which are visually similar to the true webpage. A webpage is reported as a phishing suspect if the visual similarity is higher than its corresponding preset threshold. Preliminary experiments show that the approach can successfully detect those phishing webpages for online use. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval?Information filtering; I.7.5 [Document and Text processing]: Document Capture?Document analysis. General Terms Algorithms, Experimentation, Security, Human Factors Keywords Anti-Phishing, Web document analysis, Information filtering, Visual similarity