The present invention relates to the use of an antagonist of kisspeptin in the manufacture of a medicament for the treatment of a condition induced and/or worsened by kisspeptin activity in an individual. The invention also provides certain defined peptide molecules, which may act as an antagonist of kisspeptin, which are of use in treating a condition induced and/or worsened by kisspeptin activity in an individual. In addition, the invention provides methods of identifying and/or using antagonists of kisspeptin and/or the defined peptides, and pharmaceutical compositions thereof.
