4thAD is technically correct..although HCG does stimulate endogenous testosterone production, it does not help in re-establishing the normal hypothalamic/pituitary testicular axis..the hypothalamus and pituitary are still in a refractory state after prolonged steriod useage, and remain this way while HCG is being used, because the endogenous testosterone produced as a result of the exogenous HCG represses the endogenous LH production. Once the HCG is discontinued, you still must go through a re-adjustment period..it is merely delayed by HCG use..and that is the reason you have to take clomid following HCG use.....but back to the original question..HCG definitley brings your balls back to normal size, because right now, mine are raisins and I do have HCG and clomid when I stop, I take 5000iu first week and 2500iu for last 2 weeks followed by clomid at 100mg for 5 weeks and it does the job, but I do read that some people say that they don't get atrophy, which is weird to me..mine always atrophy when I start any cycle of anything..and yes I do sometimes get shooting pain in my balls, it seems to be related to being atrophy and or using HCG, so it seems related to you endogenous testosterone lowering or increasing at a significant rate