OBJECTIVES:   The objective was to measure health states (HS) associated with Immune (Idiopathic) Thrombocytopenic Purpura (ITP), as perceived by members of the UK general public. METHODS:   Six distinct ITP HS were defined based on platelet levels, risk of bleeding, and key adverse events/disease complications. Clinical trial data on bleeding and ITP-specific quality of life data were key sources for developing HS descriptions. After a pilot survey, sample size calculation was based on combinations of detectable differences in utility scores between HS, power, and standard deviation (SD). A total of 359 respondents, who were randomly selected from a managed panel that includes 300,000 individuals in the UK, completed the web-based Time Trade-Off survey Sampling and tracking quotas on respondent demographic characteristics were performed to ensure representativeness. The Wilcoxon signed rank test was used to compare each pair of HS. RESULTS:   Sample characteristics (mean age: 47.9 years, SD: 16.9; 54% female) were comparable to the UK general population. ITP HS were valued as significantly worse than perfect health. Experiencing episodes of bleeding was a more important driver than low platelet levels in valuing a HS to be worse. Substantial disutilities were associated with surviving an intracranial haemorrhage. Mean utility scores for the ITP HSs: HS1: Platelets ≥50x109/L, no outpatient bleed: 0.863 (SD:0.15) HS2: Platelets ≥50x109/L, outpatient bleed: 0.734 (SD:0.19) HS3: Platelets <50x109/L, no outpatient bleed: 0.841 (SD:0.19) HS4: Platelets <50x109/L, outpatient bleed: 0.732 (SD:0.19) HS5: Intracranial haemorrhage (2-6 months): 0.038 (SD:0.46) HS6: Steroid treatment adverse events: 0.758 (SD:0.20) CONCLUSIONS:   This survey provided evidence that members of the UK general population associate a substantial loss of value living in ITP HS. These findings suggest an important role for new ITP treatments and utility scores gained from this survey can be used in future cost-effectiveness studies.