Semen (seminal fluid) consists of spermatozoa (sperms) and the fluid part. About 40% cases of infertility are due to abnormalities in semen and therefore semen analysis is the first test to be performed while investigating for infertility. Defect of sperms may be quantitative (absence of sperms, lack of enough sperms) or qualitative. Indications for semen analysis and collection of the sample are discussed in this chapter. Patient is asked to collect the semen by masturbation after a minimum of 2 days and a maximum of 7 days of sexual abstinence. Specimen should be collected in a clean, dry and wide mouthed plastic/glass container. Collection of condom sample is not advisable because they often contain spermicidal agents which impair the sperm motility.