The objective of this case study is to demonstrate an evaluation method for voluntary biodiversity offsets. We focus on the Antamina mine, operated by Compañía Minera Antamina S.A. (ANTAMINA). The Antamina mine is among the world’s largest copper and zinc mines, and is located in the Andean mountains in Ancash, Peru. In 2004 the company began a voluntary biodiversity conservation program to restore endangered Polylepis forests in the area around the mine. While the program was not originally designed as a biodiversity offset, the case study examines its potential to serve as one.