Nature-based tourism and recreation is a growing phenomenon around the world. In Australia, nature-based tourism represents an important part of the tourism sector and is to a large extent dependent on protected areas such as World Heritage areas, marine parks and national parks. While tourism and recreation can benefit protected areas, some are under pressure from visitation and marketing should play a role in managing visitor demand. To this end, a number of authors have suggested demarketing as a management tool to address situations of excess visitor demand, however, research on demarketing in protected areas is limited. To address this research gap, this thesis examines the use of demarketing in Australian national parks that face excess visitor demand using a case study on the Blue Mountains National Park. The thesis investigates factors that contribute to high visitor demand for the park, the use of demarketing to manage demand and factors that influence when and how demarketing is applied. Demarketing is that aspect of marketing that deals with discouraging customers in general or a certain class of customers in particular on either a temporary or permanent basis. In protected areas specifically, demarketing is concerned with reducing visitor numbers in total or selectively and redistributing demand spatially or temporarily. Six factors that contribute to high visitor demand for the national park were identified including the attractiveness of the park, its proximity to Sydney and the fact that the park is a renowned destination with icon sites. It was established that no holistic demarketing strategy is currently employed in the park and that the demarketing measures that are applied are not consciously used as demarketing. The measures used in the Blue Mountains National Park were discussed according to their association with the marketing mix components (4 Ps). Demarketing measures related to �product� include limiting recreational activities by defining specific areas where they can be conducted, limiting the duration of activities and closures of sites or features in the park. The measures related to �place� are the use of a booking system, limiting visitor numbers and group sizes, commercial licensing and limiting signage. Measures related to �price� are not extensively used in the park. The promotional demarketing measures applied include stressing restrictions and appropriate environmental behaviour in promotional material and nonpromotion of certain areas or experiences in the park. Importantly, these demarketing measures are not employed across the whole park or for all user groups, but are used for certain experiences in specific contexts and circumstances. Three types of factors influence the use of demarketing in the Blue Mountains National Park: pragmatic considerations, resource considerations and stakeholder interests. Pragmatic considerations include the feasibility and effectiveness of certain demarketing measures, which are influenced by the specific context of the national park. Resource considerations relate to financial, human and temporal resources and the findings suggest that a lack of resources influences and at times inhibits the use of demarketing measures. It was also found that various stakeholders have a profound influence on the use of demarketing measures. The stakeholder groups have diverse interests and therefore influence the use of demarketing in different ways by supporting or impeding certain measures. Based on the findings and limitations of this study, recommendations for government and future research are made. These emphasise among others the need for more consistent and comprehensive collection of visitor information to tailor management actions more effectively. It is also suggested that a more conscious and holistic application of demarketing measures may help to manage visitor demand to parks proactively to ensure that the resource remains for future generations.