In some areas, anthropogenic activity has led to a high level of environmental pollution with heavy metals that it is now detrimental to living organisms. However, there are about 500 plant species known to accumulate extraordinarily high amounts of metallic elements in their tissues without any noxious effect, and these plants, hyperaccumulators, have lately been receiving increasing interest, because of their potential for being exploited in sustainable biotechnologies such as phytoremediation and phytomining. This paper reviews on the basic mechanisms of tolerance enabling practical application of hyperaccumulating plants in the clean up of land contaminated with heavy metals.