• Reproduction function of a male broadly encompasses three interrelated and synergistic steps-the spermatogenesis, regulation of the male reproductive functions and performance of the male sexual act. • Fertilisation-a union normally of a single out of many a million sperms of a male with the egg or ovum of a female remains an intriguing phenomenon. • Successful union of ovum and the sperm does not guarantee normal development of the zygote. The sperms have two different constituents-one with ‘X’ and another with ‘Y’ chromosomes and chromosomal abnormalities could lead to faulty development of the unborn child in the forms of Klinefelter’s and down’s syndromes. • This book deals with the dysfunctions of the male reproductive system with emphasis on common condition