This article investigates the determinants of optimal capital structure in real estate investment by using a real options framework. An investor chooses a purchase date and a loan-to-value (LTV) ratio that balances the tax shield benefit and the transaction costs. After the purchase, the investor acquires the option to default. Greater uncertainty in housing price inflation will enhance this option value such that the investor will purchase earlier and reduce debt financing. This is consistent with the recent U.S. experience in which high LTV ratios were observed before and low LTV ratios were observed around the subprime mortgage crisis.