This thesis provides a theoretical analysis of off-balance sheet financing schemes and empirical evidence on the use of related companies as off-balance sheet financing vehicles. Using extant capital structure theories the thesis develops a debt structure framework in which related company off-balance sheet financing transactions are analysed as effective mechanisms for the minimisation of bankruptcy and debt agency costs. A model of the existence of related companies in group structures is developed based on the debt structure framework. The thesis provides some evidence to support the minimisation of bankruptcy and agency costs role of related companies.