In the management of asthenozoospermia, the spermogram-spermocytogram plays an important role during diagnosis. It is of major importance to distinguish between necrozoospermia and sperm vitality. An ultrastructural study of spermatozoa is processed in the case of primary infertility without female implication, severe, unexplained and irreversible asthenozoospermia, sperm vitality at least 50 % and normal concentration of spermatozoa. Ultrastructural flagellar abnormalities are numerous and involve most spermatozoa. ICSI provides a suitable solution for patients with sperm flagellar defects to conceive children with their own gametes but the rate of ICSI success may be influenced by the type of flagellar abnormality. Some fertilization and birth rate failures which are related to some flagellar abnormalities might occur.