Androgen receptors located throughout the body, regulate most, but not all actions of testosterone. This ligand regulated nuclear transcription factor has clinically significant effects in almost every organ system of the body. Studies of mutations of the androgen receptor in humans and targeted tissue-specific deletion in genetically modified animal models are powerful tools for understanding the functional role and significance of the androgen receptor. Clinically relevant human mutations of the androgen receptor are linked to the motor neurone disease, disorders of sexual development and a variety of hormone dependent tumours. Removal of the ligand testosterone in humans and mice offers further valuable insight into the role and function of the androgen receptor. This review will link androgen receptor function, as understood from animal models to human function and pathology. Tissue specific deletion of the androgen receptor in genetically modified mice using the cre-lox system will be compared to the effects of androgen deprivation in humans. Effects in muscle, bone and adipose tissue will be used to demonstrate the widespread function of the androgen receptor.