Our current data, based on a model of progressive loss of Kiss1 expression, refine those previous findings, suggesting that preservation of a minute part of kisspeptin/NKB input during the pubertal transition is sufficient to complete puberty and attain fertility in the male, with development of an infertile phenotype later in adulthood, along with a more profound perturbation of the Kiss1 system with age. This evidence concerns the gene KISS1 and Infertility.