RESUMEN
To calculate the costs of the radiology ward by step-down method in Amir Alam hospital, Tehran, Iran. By employing the Step-down cost accounting [SDCA] method, the current cost, overhead cost, capital cost and depreciation charge etc. of the radiology ward of Amiralam hospital and then considering the number of the rendered services the unit cost of such services have been calculated. Costs of the service unit computed for a simple radiology services were Rls 50,064/-, for sonography, Rls 70,300/-, and for CT scan, Rls 245,142/-. The tariffs of the Ministry of Health and medical Educations only cover about fifty percent of the said costs. The personnel costs of the unit which were Rls 1,788,100,000/-, formed about 62% of the entire costs of the Radiology Ward. In order to compute costs and use analyses of costs in the management of the hospital, we need real and available accounting data. We further need to use an identical accounting method all over the country and to save accounting information according to the computation of the costs of the service units. We can finally determine real tariffs once we do multiple researches in different hospital, using the same method