The present study was conducted on twelve adult stray dogs of age 2 – 3 years, weighing 14 - 18 kg and randomly divided into three groups. Animals in group I (n = 5) and group II (n = 5) were orally given 300 and 500 microgram coumestrol dissolved in di-methyl sulfoxide in the commercial dog treats on days 0, 7, 14, 21 and 28, respectively. Animals in control group III (n = 2) were given DMSO alone as per above schedule. Castration was done one week after the completion of the treatment. Tissues for histology and electron microscopy were fi xed in Bouin’s fi xative and Karvonsky’s fi xatives, respectively. Epithelial lining of the efferent ductules was composed of cuboidal or columnar epithelium having ciliated and non- ciliated cells. Cellular architecture of the efferent ductules was normal. Scanning electron microscopy revealed normal efferent ductules with presence of cilia on luminal surface. In conclusion, oral feeding of 300 microgram and 500 microgram of coumestrol has no adverse effects on the functioning of efferent ductules in dogs and at this dose rate, this compound cannot be used for population control of stray dogs.