The testicles are a unique male reproductive organ. Normal men have two testicles, located on the left and right side of the scrotum. The testicles are oval in shape and gray in color. The testes are 3.5-4.5 cm long, 2-3 cm wide, and 1-2 cm thick, and grow rapidly with sexual maturity. If a normal adult male has small testicles when he reaches sexual maturity, before treatment, he needs to clarify the causes of small testicles, such as testicular dysplasia, testicular inflammation, trauma, cryptorchidism, etc. Or in older men, with the decline of sexual function, the testicles may also atrophy, thus causing small testicular size. In addition, hormone levels and semen routine need to be checked. If the testicle size is only small but the hormone level and semen quality are normal, no special treatment is needed for the time being. However, if the testicular atrophy is caused by certain diseases, and the testicular function of androgen secretion and sperm production decreases, the specific cause needs to be clarified to make targeted treatment. To sum up, if the testicles are small, you need to know the specific cause and whether there is a decrease in testicular function to make targeted treatment.