Semen analysis is used both as an indicator of infertility as well as a basis for treatment. However a semen analysis gives poor discrimination between infertility and fertility and is only of real value in indicating infertility when the variables within the semen analysis are at their extremes. The reason that a semen analysis is a poor discriminator of fertility is clear as the difference between a conception and a non conception cycle involves one single sperm: in a conception cycle all sperm are lost while in Abstract of the 8th Royan International Twin Congress, Tehran, Iran, 5-7 September 2007 14 Yakhteh Medical Journal, Vol 9, Sup 1, Summer 2007 a conception cycle all but one sperm are lost. Therefore the number of motile and morphologically normal sperm can only give the clinician a probability of pregnancy. Thus wether the count is 10% more or 10% less can make little difference clinically. For this reason accurate sperm counts are unnecessary in clinical andrology. Only when all the sperm in an ejaculate show an abnormality can a semen sample truly be said to be infertile. One important aspect of infertility management is to arrive at a clinical diagnosis. Only with a clinical diagnosis can both the pathophysiology underlying patients infertility and the generation of an abnormal semen analysis be determined and understood. Only with an understanding of the causation of infertility can any preventative measures be taken, can any rational treatment be provided and the frequently unwarranted use of IVF be avoided. In the male, treatment often relates solely to the sperm count and not its underlying cause. Much of the causation of male infertility in clinics today goes undiagnosed. In my recently completed (but unpublished) study of testicular ultrasound among a group of 749 men attending an infertility clinic, a large of amount, much of male infertility will remain misunderstood.