Abstract: On the basis of the experimental results it has emerged that relaxin has a pro-differentiating effect on stem cells. It is therefore suggested the use of this hormone as principal component of a drug for the treatment of all those situations that find or will find benefit from the use of stem cells for the reconstruction of tissues damaged by traumatic events or by ischemic-inflammatory-degenerative diseases. It is also suggested the use of relaxin for the treatment of syndromes deriving from the missing activation of stem cells during fetal development (at subsequent somatic-functional maturation), such as for example hypogonotropic hypogonadism with anosmia (Kallman's syndrome).