It is generally agreed that the testis is under endocrine control from the pituitary, and is influenced by physiological and paracrine factors within the organ. The aim of this study is to analyze the effect of unilateral and bilateral epididectomy on the testicular tissue growth of rats. Twenty- one male old Sprague-Dawley rats (28 days old) were used in the study. Rats were assigned into 3 equal groups. The first group was the control group, while unilateral and bilateral epididectomy was performed on the second and third groups, respectively. Twenty-one days after the epididectomy, testicular tissues from each group were taken and fixed in Bouin solution. Paraffin sections were stained with Haematoxylin and Eosin, Vangiesson, PAS-Hemalun and examined by light microscopy. Disorganization of the germinal epithelium, desquamation, degeneration and edema in interstitial tissue was seen in the testicular cross sections of the unilateral group. Arrest in spermatozoon stage in some tubules and presence of eosinophylic stained multinucler bodies were recognizable. In the bilateral group, degeneration and atrophic status in the seminiferous tubules of the bilateral group was observed preciesly, and occasional interstitial edema and perforations in the basal lamina were recognizable. In addition, vasodilatation, arrest in spermatozoa stage and multinucleated bodies in some of the seminiferous tubules lumen were observed in some testicular cross sections of this group. As a result, epididectomy causes degeneration in the germinal epithelium and hypoplasia in Leydig cells. It is concluded that epididectomy causes degeneration in the germinal epithelium, interruption of spermatogenesis, and a notable decrease in the number of Leydig cells. Key Words: Epididymectomy, Testicular, Rat Ratlarda Unilateral ve Bilateral Epididymectomy’in Testisler Üzerine Etkisi ÖZET Unilateral ve bilateral epididymectomy’in sıçan testis gelişimi üzerindeki etkisini araştırmak amacıyla bu çalışma planlandı. Çalışmada 21 adet 4 haftalık erkek Spraque-Dawley sıçan kullanıldı. Denek hayvanları 3 eşit gruba bölündü. Birinci grup kontrol, ikinci gruba unilateral epididektomyi ve üçüncü gruba ise b,lateral epididymectomy uygulandı. Epididymectomy sonrası 21. günde her üç grubun testis dokuları alınarak Bouin solüsyonunda fikse edildi. Parafin kesitler Hematoksilen-Eozin, Hematoksilen- Vangiesson ve PAS-Hemalun ile boyanarak ışık mikroskobunda incelendi. Unilateral grub testis kesitlerinde germinal epitel ayrışması, deskuamasyon, dejenerasyon ile interstisiel dokuda ödem görüldü. Bazı tubüllerde spermatozoon aşamasında arrest durum ve eozinofilik boyanan multinükler hücrelerin varliğı dikkat çekiciydi. Bilateral grupta ise, testis tubüllerindeki dejenerasyon ve atrofik durum ileri derecede izlenirken, yer yer intertisiel ödem ve bazal laminada perforasyon dikkat çekiciydi. Yine bu grubun bazı testis kesitlerinde vazodilatasyon, spermatozoa aşamasında arrest durum ve bazı seminifer tubül lümeninde multinükler hücreler bu grupta da izlendi. Sonuç olarak, epididektomi testis germinal epitelinde dejenerasyon ve Leydig hücrelerinde hipoplaziye neden olmaktadır.