The Sertoli-cell-only syndrome is a special form of testicular failure. It should be considered when azoospermia is found. Histological examination reveals the absence of spermatogenetic cells, which is the only pathology in most cases. In a minority of patients, dysregulation in the pituitary-testicular axis can be observed. Another possible feature consists of microdeletion of the long arm of the Y chromosome. A specific treatment does not exist at this time. In incomplete SCOS, fertilization may be achieved by intracytoplasmic sperm injection (ICSI) after testicular sperm extraction (TESE).