Rehman R, et al. - A cross-sectional study was conducted on 80 males (44 infertile and 36 fertile) and 88 females (44 in each group) by the experts in order to investigate the role of kisspeptin (KP, a peptide hormone, plays a pivotal role in fertility and neuroendocrine regulation of hypothalamo–pituitary-gonadal axis) on hypothalamo–pituitary-gonadal axis by contrasting the levels of kisspeptin in fertile and infertile subjects and recognizing single nucleotide polymorphisms (SNPs) of KISS1 gene in exon 2 and exon 3 of infertile male and female cohorts. In contrast to infertile female subjects, significantly great levels of KP, follicle-stimulating hormone (FSH), luteinizing hormone and testosterone were observed in the fertile male and female subjects except for the low FSH levels. With low KP and hormonal levels, 1 polymorphism in exon 2 and three in exon 3 in the infertile group was discovered. Male subjects had abnormal sperm parameters and failed attempts of intracytoplasmic sperm injection in females. Therefore, in the release of reproductive hormones and gonadal functions, expression of SNP in exon 2 and exon 3 of KISS1 could be responsible for the alteration, hence resulting to infertility.