OBJECTIVES: To quantify UK psoriasis patients’ tolerance for serious side-effect risks associated with biologic treatments relative to the value of symptom improvements METHODS: Members of a UK psoriasis patient organization were invited to complete an on-line conjoint-analysis survey which evaluated efficacy and safety features of biologic treatments for psoriasis. Patients’ trade-off preferences for improvements in the severity and coverage of psoriatic lesions were elicited, as well as treatment-related risks of tuberculosis (TB), serious infections, and lymphoma. The choice pattern observed in the data was used to estimate preference weights which indicated patients’ relative trade-off preferences among treatment outcomes.Preference weights were used to derive maximum levels of side-effect risks that patients would accept for various improvements in psoriasis symptoms. The DLQI was used to assess the impact of psoriasis on patients’ quality of life. RESULTS: 159 people with a self-reported physician diagnosis of psoriasis completed the survey. Mean age was 39 years and most respondents reported having psoriasis for at least 5 years. Also, the mean DLQI score was 11. Respondents would accept up to 0.39% of treatment-related risks of lymphoma for reducing the area covered by a severe lesion from 25% to 10% of their torso, and up to 0.60% if lesions were on their arms or legs.For the same improvement in symptoms, respondents would accept up to a 2.3% risk of TB or 3.3% risk of serious infections if the lesions were on their torso, and a 3.6% risk of TB or 5.2% risk of serious infections if the lesions were on their arms and legs. CONCLUSIONS: Psoriasis patients’ tolerance for side-effect risks varies with side-effect severity and location of lesions. Estimates of patients’ risk tolerance for serious side-effects indicate that patients value psoriasis symptom control further confirming that psoriasis has a  significant effect on patients’ quality of life.