The effects of ligation of the vas deferens, the corpus epididymidis and the vasa efferentia on the testicular function were studied in sexually mature rats. The significant decrease in the testicular weight was observed after ligation of the corpus epididymidis and the vasa efferentia. However, neither the weight of the ventral prostate and of the seminal vesicle, nor the plasma testosterone level showed significant changes. The results suggest that the ligation at the three locations would nott affect the endocrine function of the testis. The changes in the testis would mainly affect the spermatogenesis. The effects of sperm stasis on the testicular function were also discussed.