The use of computer asisted semen analysis has advanced the ability to study and understand sperm function as it relates to human infertility. The major advances have been in the ability to more accurately determine sperm concentration (counts) and motility (movement). Generally, sperm are “looked” at by a computerized digitizing tablet through a microscope. The computer has been “taught” by the laboratory personnel what sperm look like, and how they move. When the computer then “sees” a sperm under the microscope, it is able to draw a digitized picture of each individual sperm, including the speed and path this sperm takes while moving under the microscope. A great deal has been learned about the normal and abnormal “micro”characteristics of sperm employing this method. The method is, however, not foolproof. The computer is only as intelligent as it’s programmer. Small changes in the computer program can alter the sperm calculations significantly. The computers must constantly be monitored and updated. In most laboratories, all grossly abnormal CASA assays are always verified by both a repeat analysis as well as with a “hands on” human second look opinion. We feel that any abnormal sperm count must be verified by a manual counting and assesment method.