Abstract: Objective: To evaluate CT in diagnosis of renal milk of calcium (RMC).Methods: The X-ray films and CT findings of 12 cases of RMC were reviewed by two experienced radiologists by double blind method.All the cases underwent anterior-posterior and lateral abdomen plain film examination and non-enhanced CT scans.Among them,3 cases were performed enhanced CT scan.Results: The CT findings clearly displayed the whole view of milky calcium cyst and its'half-moon'sign.The half-moon's high density shadow formed by RMC was always located in the lowest part of the lesion.The cyst type and hydronephrosis type were observed in 5 cases and 7 cases respectively;the lesions of all but 2 cases were unilateral;RMC accompanied by renal stone was found in 2 cases.Four cases of RMC were misdiagnosed as renal stone and 2 cases were miss-diagnosed by X-ray.Conclusions: CT plays an important role in diagnosis of stone and its sensitivity is superior to X-ray films.