In current study, ethyl-morphine (em) was synthesized from the morphine and glucuronidated via enzymatic mechanism. The conjugated glucuronide ethylmorphine (em-glu) was radiolabeled with I-131 using iodogen method. The quality control studies of radiolabeled compound (I-131-em-glu) were done with Thin Layer Radio Chromatography to confirm the radiolabeling efficiency. Biodistribution studies of I-131 labeled em-glu were run on healthy male Albino Wistar rats. The distribution figures demonstrated that I-131-em-glu was eliminated through the small intestine, large intestine and accumulated in urinary bladder both receptor blocked and unblocked biodistribution studies. A greater uptake of the radiolabeled substance was observed in the m. pons, hypothalamus and mid brain than in the other branches of the rats' brains.