Oligospermia can have many causes. One of the most common causes in men is varicocele. Oligospermia can occur in the presence of varicocele. It may improve after varicocele surgery, but sometimes it may not improve or may even worsen. Besides varicocele, various infections, premature ejaculation, frequent ejaculation, or prolonged abstinence can lead to oligospermia. In infants with undescended testes, if surgery is performed after the age of 2, oligospermia is commonly observed. Parents should pay close attention to this issue. Infants with undescended testes should undergo surgery before the age of 2 without delay. In addition, chromosomal abnormalities can cause oligospermia, as can celiac disease. Some surgeries, such as those for hernia repair, can result in oligospermia. Long-term exposure to certain chemicals such as dyes, pesticides, and lead can also cause oligospermia. Tobacco use, obesity, depression, and excessive alcohol consumption can also lead to oligospermia.