Fiscal regime governing contracts is one of the main aspects of differences between petroleum contracts with each other. To design a suitable fiscal regime, economic considerations are on the top of priority. Comparing Buy-Back contracts with new Iran Petroleum Contract (IPC) shows that Buy-Back contracts have intrinsic problems such as being short term, having a disintegrated chain of production, faulty tax system and having cost based fiscal system. While IPC is long-term contracts with an integrated chain of production and the contractor has an incentive for cost saving (but with the same faulty tax system). On the other hand, comparing the net present value of contractor take shows that IPC could have been more desirable and cost-effective in Azadegan oil field than Buy-Back contracts.