Background. In Papua New Guinea (PNG) there continues to be considerable interest in developing a health system that incorporates both traditional and western medicine. A policy on traditional medicine has recently been endorsed. Simultaneously, there is limited information about the traditional beliefs and practices that influence treatment-seeking behaviour.

Aim of the study. A case study among the Nasioi people of Bougainville was conducted to gather information that could help to inform the implementation of the National Policy on Traditional Medicine for PNG.

Research objectives. The main objective of the case study was to describe how health knowledge and belief systems influence treatment-seeking behaviour, specifically in relation to the use of traditional and western health care systems. The study also sought to develop an explanatory model for decision-making responses to febrile illnesses and skin conditions.

Methodology. By using a non-experimental, cross-sectional study design and focused ethnographic approach, a sample of 200 Nasioi community members were interviewed by Nasioi-speaking research assistants.

Results. The study found that people in the sample group subscribe to both traditional and western medical paradigms. Western medical concepts have been assimilated but have not displaced traditional understanding of illness. There was congruence between beliefs about causes of illness, treatment-seeking responses to illness and stated or hypothetical preferences for traditional or western medicine. Data obtained in each of these domains reflect concepts of illness derived from both medical paradigms and demonstrate participants’ confidence in the efficacy of both traditional and western medicine.

Conclusions. It is proposed that a health system that incorporates traditional medicine may be better aligned with people's concepts of illness than the current system. Because it is more consistent with Nasioi concepts of illness, an incorporated health system may lead to more appropriate health service utilisation and, ultimately, to improvements in population health status.