Low sperm counts, abnormal sperm morphology (shape), and low sperm motility are usually asymptomatic conditions to most males. Most cases of low sperm counts are "idiopathic" or unexplained. Some cases are associated with a swollen varicose vein in the scrotum, called a varicocele.

Some simple abnormalities may be improved by reducing stress, reducing heat to the genitals (eg. avoidance of tight clothing, saunas or hot tubs), or by changing harmful lifestyle habits (avoiding tobacco, alcohol, or drugs such as marijuana). Short term illnesses, significant stressful periods, and some medications may temporarily affect sperm counts.

Some of the causes of male infertility:

1. Exposure to hazardous toxins, chemicals, or radiation
2. Infections such as mumps, or venereal diseases
3. Testicular injury (sports or work injury)
4. Childhood illness (failure of a testicle to descend properly)
5. Blockage of one of the ducts allowing flow of sperm from the testicle
6. Injury, infection or prior vasectomy
7. Genetic absence of these ducts (cystic fibrosis)
8. Immune reaction against sperm (antisperm antibodies)
9. Testicular failure and other hormonal problems
10. Chronic medical illness (thyroid disease, diabetes, and hypertension)
11. Spinal cord injuries and paralysis
12. Varicocele