This essay explains the role of reproductive science, including what are termed reproductive technologies (i.e. artificial insemination, in vitro fertilization, embryo transfer, cloning), in conservation biology. Reproductive techniques (high- and low-tech) find their greatest application in understanding species uniqueness, adaptations and physiological mechanisms, not in the large-scale assisted breeding and the production of offspring. Models of how to use these tools to study reproductive fitness are emerging to help insure gene diversity and even propagate endangered species, but only after fundamental databases have been developed. Examples are provided of how non-invasive hormone metabolite monitoring, artificial insemination and genome resource banking are being used ex situ and in situ to understand wildlife biology. We predict that as the fundamental, multi-species database grows, so will the applied benefits for: (1) developing genome banks for insuring extant genetic diversity; (2) assessing the relationship of physiology, behaviour and environmental perturbations; (3) managing small populations; and (4) dealing with dilemmas ranging from contraception to skewed sex ratios to animal welfare. Most progress will be made in using these tools in systematic studies to solve the mystery of how thousands of unstudied species reproduce. Carried out appropriately, financial costs will be consistent with any approach for generating sound scientific knowledge.