Causes of infertility: 1. Congenital factors (cryptorchidism and testicular hypoplasia, congenital absence of the vas deferens) 2. Acquired genitourinary anomalies (obstruction, testicular torsion, testicular tumors) 3. Infections of the genitourinary tract 4. Elevated scrotal temperatures (e.g., consequence of varicocele) 5. Endocrine disorders 6. Genetic anomalies 7. Immunological factors 8. Systemic disorders 9. Exogenous factors (drugs, toxins, Radiation and heat) 10. Idiopathic factors (40-50% of patients) The main prognostic factors affecting infertility are: 1. Duration of infertility 2. Whether the infertility is primary or secondary 3. Results of semen analysis 4. Age and fertility of the woman