| Pretesticular | Testicular | Posttesticular |
| Endocrine (Reduced hormone production from hypothalamus/pituitary) | Genetics : Klienfelter’s syndrome, Y chromosome microdeletion | Obstruction : Epididymal , Ejaculatory Ducts, Vasa Deferens |
| Erectile Dysfunction | Congenital : Cryptorchidism | Infection |
| Antispermatogenic agent : heat, chemotherapy, radiation, drugs | Surgery | |
| Vascular : Torsion , Varicocele | ||
| Immunological |