The specific roles and direct involvements of autonomic innervations on the spermatogenic process are poorly understood. The aim of this study was to investigate stereologically the relative importance of sympathetic innervations in testicular parenchyma rats in chemically sympathectomized with guanethidine. Treated animals (n=10) were injected intraperitoneally with guanethidine at doses of 10mg/kg/day for 15 days while control animals (n= 5) received an equivalent volume of saline. After routine histological procedures, 5mum thick sections of the testes were selected for examination. Organ volumes were estimated using the Cavalieri Principle of volume measurement by means of consecutive serial sections, using "J Images" software in a computer. At least 10 seminiferous tubules were selected randomly and measured per cross section for evaluation of epithelial heights, luminal diameter and total seminiferous tubule diameter. Testicular volumes and seminiferous tubule measurements of treated animals were found to be affected by the chemical sympathectomy with guanethidine with a a statistically significant difference between experimental and control group (p<0.01). Our findings indicate that chemical sympathectomy with-short term low dose guanethidine might display morphometric changes in the rat testis which indicate the presence of autonomic innervation of its parenchyma.