HCG works by mimicking leutenizing hormone directly at the testes,causing them to produce more testosterone...Clomid works by blocking estrogen's signal at the hypothalamus and pituitary,causing them to produce their respected hormones which in turn stimulate the testes to produce more testosterone...Clomid starts the production process at its root of developement,HCG provides a temporary "workaround".For long-term recovery,clomid is mandatory...