The androgen receptor is a key transcriptional factor for the proper sex development — especially in males — and the physiological balance of all the tissues that express this receptor. The androgen receptor is involved in several pathologies and syndromes, such as the spinal and bulbar muscular atrophy or androgen insensitivity syndrome, among others, for which there is no specific treatment. Regarded as the main initial and progression factor in prostate cancer — the second most common malignant disease in men in industrialized countries — this receptor has been, for decades, the main therapeutical target for the treatment against this disease.