Biodiversity offsets are voluntary conservation activities that are designed to offset residual, unavoidable damage to biodiversity caused by development activities. The concept is also known by terms such as setasides, compensatory habitat, and mitigation banks. Recent legislation in New South Wales (Australia) provides an additional legislative tool in the attempt to counter balance biodiversity loss due to expanding urbanisation. A key role is played by the consultant ecologist who is at the interface between other vested interests: governments, the legal system, developers, and landholders wishing to trade biodiversity credits. In this paper we reflect on the role of the consultant ecologist in the biodiversity offset ("BioBanking") process, and touch on some of the pitfalls including the lack of knowledge of the function and components of most ecosystems, the immaturity of the scientific disciplines that underpin decision making, and problems on ensuring integrity of objectivity and independence in such schemes.