Operating room services are one of the major cost and revenue-generating centres of a hospital. The cost associated with the provisioning of operating department services depends on the resources consumed and the unit costs of those resources. The objective of this study was to calculate the cost of operation theatre services at Jai Prakash Narayan Apex Trauma Centre, AIIMS, New Delhi. The study was carried out at the operation theatre department of Jai Prakash Narayan Apex Trauma Centre (JPNATC), AIIMS from April 2010 to March 2011 after obtaining approval from concerned authorities. This study was observational and descriptive in nature. Traditional (average or gross) costing methodology was used to arrive at the cost for the provisioning of operation theatre (OT) services. Cost was calculated under two heads; as capital and operating cost. Annualised cost of capital assets was calculated according to the methodology prescribed by the World Health Organization and operating costs were taken on actual basis; thereafter, per day cost of OT services was obtained. The average number of surgeries performed in the trauma centre per day is 13. The annual cost of providing operating room services at JPNATC, New Delhi was calculated to be 197,298,704 Indian rupees (INR) (US$ 3,653,679), while the per hour cost was calculated to be INR 22,626.92 (US$ 419). Majority of the expenditures were for human resource (33.63 %) followed by OT capital cost (31.90 %), consumables (29.97 %), engineering maintenance cost (2.55 %), support services operating cost (1.22 %) and support services capital cost (0.73 %). Of the total cost towards the provisioning of OT services, 32.63 % was capital cost while 67.37 % is operating cost. The results of this costing study will help in the future planning of resource allocation within the financial constraints (US$ 1 = INR 54).