Today, the implementation of high quality and efficient Requirement Engineering (RE) practices in agile software development projects, is gaining great importance. Practitioners and researchers seeks for lighter RE practices that can handle the issues of abstract, unclear and changing requirements, and at the same time that can satisfy the Agile Manifesto philosophy. This study examines importance of RE practices in agile software development projects, and explores which aspects of the RE practices are perceived as most critical and how such aspects are adapted in practice today through two different agile software development projects of a case organization. This study aims to contribute agile RE literature by providing an interpretive analysis on perception of agile RE practices from different perspectives (agile team members, product owners, some top executives). Within this context, this study draws lessons from case studies and presents beneficial agile RE guidelines for practitioners and researchers.