Although deteriorating effects of unilateral spermatic cord torsion are generally accepted, the mechanism remains controversial. An experimental study was performed to evaluate the necessity of testicular and spermatogenetic material for contralateral testicular deterioration following unilateral spermatic cord torsion in rats. The animals were allocated to four groups: control, spermatic cord torsion, subepididymal orchiectomy, and spermatic cord torsion 14 days after subepididymal orchiectomy. The testes were removed on the 14th days and mean seminiferous tubular diameters and mean testicular biopsy scores were determined. Although contralateral testicular deterioration was more pronounced in the presence of testicular tissue, the absence of testicular tissue and/or spermatogenetic material did not prevent its occurrence. This is highly suggestive that autoimmune mechanism does not play a role in contralateral testicular damage following unilateral spermatic cord torsion.