Financial sustainability plans (FSPs) were developed by over 50 of the world's poorest countries receiving funding support from the Global Alliance for Vaccines and Immunization (GAVI) to introduce new and underused vaccines, injection safety and immunization service support between 2000 and 2006. These plans were analysed with respect to the strategies selected to promote financial sustainability, allowing classification of FSP strategies in three areas: (1) mobilizing additional resources, (2) increasing the reliability of resources, and (3) improving program efficiency. Despite some country successes and the magnitude of planned financial sustainability strategies, huge funding gaps remain for these countries due to the initial underlying assumptions of the GAVI and financial sustainability plan model.