How can effective patient-provider relationships be developed when the underlying cause of the health condition is not well understood and becomes a point of controversy between patient and provider? This problem underlies the difficulty in treating medically unexplained symptoms and syndromes (MUS; e.g., fibromyalgia, chronic fatigue syndrome), which primary care providers consider to be among the most difficult conditions to treat. This difficulty extends to the patient- provider relationship which is characterized by discord over MUS. In this article, we argue that the key to improving the patient provider relationship is for the patient and provider to develop congruent illness perceptions about MUS.