Hi there, Yes, low testosterone definitely causes azoospermia. Low testosterone is basically a part of hypogonadism which could be primary or secondary. Hypogonadism means gonads (testes in this case) are not functionally normally and two important functions of testes are to produce testosterone and production of sperms. In hypogonadism, one or both these functions may be hampered, depending upon the cause. But in most of the cases, the two are commonly found together. Because formation of sperms is dependent upon adequate production of testosterone. You should be consulting an Endocrinologist for this problem, in my opinion. Hope I was able to help.