in vivo assay method in vivo efficacy method Any study performed in a whole, living organism (usually an animal such as a mouse or rat), to test the effects of a treatment on a specific disease modeled in this animal. Study design and measured endpoints vary tremendously and depend on the particular aspects of the targeted disease. Ideally, the endpoints measured will correlate with how efficacy would be measured in humans. Date from BAE: 9/30/2016 PubChem AID: 687012