BACKGROUND No study has addressed the experiences of Iranian nursing students learning and using nursing theories. OBJECTIVE We investigated the experiences of Iranian postgraduate nursing students learning and using nursing theories. METHODS A qualitative study was conducted on 25 Master's degree nursing students who had completed the course of nursing theories in three selected nursing schools in Iran. Semistructured interviews were conducted. Data analysis was performed using a content analysis approach. RESULTS Most of the students had positive experiences of learning and using nursing theories. Three main categories emerged from the data namely "a refreshing opening," "needing support," and "clinical usefulness." Nursing theories refreshed the students' view of the nursing profession, strengthened their professional values, helped them recognize professional boundaries, and practice a comprehensive care. CONCLUSIONS The nursing education system should prepare expert teachers for teaching nursing theories. Nursing managers should support nurses to implement these theories.