Male infertility refers to the inability of a male to achieve a pregnancy in a fertile female. In humans it accounts for 40-50% of infertility. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity.

Pre-testicular causes:

Pre-testicular factors refer to conditions that impede adequate support of the testes and include situations of poor hormonal support and poor general health including:
- Hypogonadism due to various causes
- Drugs, alcohol, smoking
- Strenuous riding (bicycle riding,[6] horseback riding)
- Medications, including those that affect spermatogenesis such as chemotherapy, anabolic steroids, cimetidine, spironolactone; those that decrease FSH levels such as phenytoin; those that decrease sperm motility such as sulfasalazine and nitrofurantoin
- Genetic abnormalities such as a Robertsonian translocation

Testicular factors
 

Testicular factors refer to conditions where the testes produce semen of low quantity and/or poor quality despite adequate hormonal support and include:
- Age
- Genetic defects
- Abnormal set of chromosomes
- Klinefelter syndrome
- Neoplasm, e.g. seminoma
- Idiopathic failure
- Cryptorchidism
- Testicular cancer
- Retrograde ejaculation
- Ejaculatory duct obstruction
- Hypospadias
- Impotence
- Defects in USP26 in some cases
- Acrosomal defects affecting egg penetration
- Idiopathic oligospermia - unexplained sperm deficiencies account for 30 % of male infertility.


Sperm sample:

• 
  Main article: Semen analysis
  Further information: Semen quality
  The volume of the semen sample, approximate number of total sperm cells, sperm motility/forward progression, and % of sperm with normal morphology are measured. This is the most common type of fertility testing.[13] Semen deficiencies are often labeled as follows:
  - Oligospermia or **Oligozoospermia - decreased number of spermatozoa in semen
  - Aspermia - complete lack of semen
  - Hypospermia - reduced seminal volume
  - Azoospermia - absence of sperm cells in semen
  - Teratospermia - increase in sperm with abnormal morphology
  - Asthenozoospermia - reduced sperm motility
   

• There may be combinations of above as well.

What Are the Options for Male Infertility Treatment?

Some causes of male infertility are treatable or correctable through surgery. Options for treatment may include:

- Treatment with antibiotics, in cases of infection
- Surgical correction, in order to remove a varicocele, reverse a vasectomy, or repair a duct obstruction
- Medications or fertility drugs to improve sperm production
 

In cases where the above treatments are unsuccessful, or when the cause for male infertility is unknown or untreatable, IUI treatment or IVF treatment may be suggested.