Background:Accidental diagnosed of Dioctophyma renale parasite in experimental mice as the case in our report. Methods: Dioctophyma renale larvae had been reported in the renal pelvis of mice used for experimental studies. The parasite had two locations an intra-renal location (renal pelvis) and an extra-renal one (renal fat). Results: The larvae in the first location causing obvious pathomorphological changes in the renal tissues, consists of atrophy of the renal tubular epithelium dilation of the nephron. The glomerular tuft was also atrophied and it's Bowmen's were dilated. The parasite in the external location was confined by encystment were not associated with any pathological lesions.  Conclusion: It had been concluded that Dioctophyma renale had been reported for the first time in mice and were associated with acquired polycystic kidney.