Despite the 1990 reforms to the health system in Namibia, mental health still receives low priority. Coupled with limited resources, health policies are directed at addressing communicable and life-threatening diseases. On the primary health care (PHC) level, health care services are either completely absent or, at best, fragmented. Therefore, an assessment of the implementation of the mental health policy that was launched in 2005 in the Oshana region of Namibia was undertaken in order to assess the extent to which the mental health policy had been implemented. The aim of the study was to explore and describe the extent of implementation and identify the challenges faced by nurses in PHC settings.A quantitative, explorative, descriptive design was used, where a total of 42 nurses from 13 health facilities in the Oshana region were conveniently included in the study. Data were collected using a self-administered questionnaire that included both open and closed-ended items. The study found that health care workers on the ground were expected to implement the policy, without have been provided with the crucial tools for implementing it, such as training, implementation guidelines, supervision, infrastructure to support the services and the materials needed to provide the services. In addition, although 77% of the research participants had received training in mental health, none expressed confidence in delivering mental health services on a PHC level. As a result, such services are not available in 94% of the health facilities in the region. This finding supports Gilson et al.'s (2008) bottom-up model of policy implementation, which holds that in order to implement a policy fully and successfully, sufficient resources for implementation at multiple levels are required.The findings call for articulated plans to address the challenges experienced in mental health policy implementation in Namibia in order to allow for the early identification of the burden associated with mental disorders.