Infertility with azoospermia requires a diligent search for reversible factors and treatment to restore natural fertility, even though most cases are due to untreatable primary spermatogenic failure and are destined to require consideration of assisted reproductive treatment (ART) options. Complete clinical and diagnostic evaluation is essential for avoiding both unnecessary ART and overlooking important co-morbidities. Gonadotrophin deficiency is the most treatable cause, resulting from drug effects or congenital or acquired disease, and medical therapy is highly efficacious. A range of uncommon endocrinocrinopathies may also result in reversible azoospermia. Finally, obstructive azoospermia may be surgically remediable in selected cases.