This paper presents an innovative expert usability evaluation method called DEPTH (usability evaluation method based on DEsign PaTterns & Heuristics criteria). DEPTH is a method for performing expert-based scenario driven heuristic usability evaluation of e-sites. DEPTH focuses on the functionality of e-sites and emphasizes on usability characteristics within their context. This can be done not only by examining the availability of functionality of an e-site but also the usability performance of the supported functionality according to specific context related usage scenarios. Scenario driven expert based usability evaluation/inspection is resource demanding. Moreover, it is not easy to find usability experts for specific types/genres of e-sites. Thus, the main motivational idea for proposing DEPTH have been: i) to minimize the preparatory phase of a usability evaluation process by re-using inspection scenarios and ii) to assist a novice usability evaluator (one who is not necessarily familiar with the genre of the e-site) by showing best design practices. Thus, DEPTH proposes the (re) use of expert’s knowledge captured in design patterns. This paper briefly describes the DEPTH method and presents findings from applying it to a usability evaluation study of e-travel sites.