OBJECTIVES: Biologic treatments have improved outcome for immunology diseases in the last decades globally. However, biologic penetration in China is lower compared to developed countries. This study aims to explore the willingness-to-pay (WTP) for biologics in immunology diseases in China by understanding decisions driving physicians’ prescribing behavior and patients’ payment. METHODS: Primary market research was done by interviewing 160 physicians with biologic experience, 200 patients consisting of patients who have not received any biologic treatments before (bio-naïve), and patients with biologic experience (bio-experienced) from  large hospitals (tier 3A) in Tier 1 and 2 cities. Patients were recruited with a diverse set of affordability as measured by household incomes. RESULTS: The results show that patients rely on physicians for treatment recommendation.  For rheumatoid arthritis, ankylosing spondylitis, and psoriasis, the top four factors driving physician’s recommendation are drug cost, patients’ ability-to-pay, safety of treatment and efficacy of treatment. For Ulcerative Colitis (UC) and Crohn’s Disease (CD), the top four factors were safety, efficacy, patients’ affordability followed by drug cost. The difference in pattern for UC and CD is likely attributed to the more severe nature of these diseases. Other factors such as injection frequency and mode of administration ranked lower for all indicators. CONCLUSIONS: Patients interview results show that ≈60% of bio-naïve patients were rejected biologic treatment due to cost; ≈30% of bio-experienced patients stopped biologic treatments due to cost. This confirms that affordability considerations do limit the potential benefit that biologic treatments can provide. Interestingly, ≈30% of bio-experienced  patients have stopped biologic treatment as it was perceived that treatment course was completed. This could be attributed to how physicians perceive biologics to be used. While affordability limits biologic penetration in auto-immune diseases in China, there are other considerations e.g.  the severity of diseases and physician perception of treatment paradigm.