It is normal for two testicles to be different sizes. The vast majority of male patients have two testicles that are not the same size, but the difference is not significant. If there is testicular trauma, or if the testicles descend late, it is possible that both testicles are not the same size. It is recommended to go to the hospital for examination to observe whether the testicles are within the normal size range and to observe whether the blood flow to the testicles is normal. There are some patients because of late testicular descent and delayed testicular development, in which case the testicular size difference is relatively large. There are also some patients because the blood supply to the testicles is very poor after the testicular trauma, resulting in testicular atrophy, which will also lead to the different size of the testicles on both sides. As long as the difference in testicular size between the two sides is not large, it is usually normal.