Helical tomotherapy is a relatively new modality with integrated treatment planning and delivery hardware for radiation therapy treatments. In view of the uniqueness of the hardware design of the helical tomotherapy unit and its implications in routine clinical practice, the Therapy Physics Committee (TPC) of the American Association of Physicists in Medicine (AAPM) commissioned Task Group 148 (TG‐148) to review this modality and make recommendations for quality assurance related methodologies. This report summarizes the findings of the Task Group and aims to provide the practicing clinical medical physicist with the insight into the technology that is necessary to establish an independent and comprehensive quality assurance program for a helical tomotherapy unit. In this task group report an overview of the TomoTherapy system and its unique aspects is provided. Delivery, imaging, and treatment planning quality assurance are discussed in three separate chapters of this report. Lastly quality assurance aspects are summarized according to their recommended frequency.