Nanotechnology is considered as an industrial revolution of the third millennium. Advances have a remarkable impact on different fields such as medicine, engineering, economy and even politics. However, a wide range of ethical issues has been raised by this innovative science. Many authorities believe that these advancements could lead to irreversible disasters if not limited by ethical guidelines. Involvement of developing countries in new fields of science could be associated with substantial advantages. In this paper, we intend to review main ethical issues of nanotechnology, taking into account the surge of interests in this field and the ever-increasing advances of nanotechnology in Iran. The issue of safety, considering environmental and ecological impacts of nanoparticles (smart dust), and standards of customer awareness are important debates. The 'Grey-goo' scenario and the concerns about 'post-humanism' are also discussed by bioethicists. There are further concerns about justice, intellectual property rights, accountability, and the probability of military and security misuse.