Background To enable decisions about investment across different areas of health care, health needs to be measured in a standardised way. In the UK, the quality-adjusted life-year (QALY) is the preferred metric. However, no measure of the QALY loss associated with measles is available, either for the UK or elsewhere. This study aimed to estimate the quality of life effect of measles by surveying patients with measles in England. Methods We did a population-based prospective study using postal questionnaires to request information about people's illness along with an age-specific EQ-5D—a validated questionnaire commonly used to quantify QALYs. Public Health England reported 3207 laboratory-confirmed cases of measles in England between Jan 1, 2012, and June 30, 2013. Beginning in June, 2012, cases confirmed by IgM detection or PCR, or both, were sent postal questionnaires. Individuals with laboratory-confirmed measles reported in travellers communities were not invited to participate in the study. Public Health England engages with this community through different protocols and procedures. Public Health England has ethics approval to conduct enhanced outbreak surveillance. This approval includes the collection of health-related quality of life (HRQoL) data. Consent was implied through the return of a completed questionnaire to Public Health England. Findings 507 questionnaires have been sent to individuals with confirmed measles; 203 have been returned (40·0%). The mean HRQoL loss per measles case was the equivalent of 6·9 days (95% CI 6·0—7·8), or 0·019 QALYs, after undertaking a missing value regression analysis. 37 (18·2%) of 203 responses were from parents or guardians of patients less than 1 year old. There was no evidence that patients who were hospitalised were more likely to respond to the questionnaire. 196 (96·6%) of 203 patients reported at least one complication, including fever (187 [92·1%]), conjunctivitis (114 [56·2%]), and difficulty breathing or coughing (162 [79·8%]). The mean duration of illness was 13·8 days (95% CI 12·5—15·1). 128 (63·1%) of 203 patients recorded absence from work or school, with a mean duration of 9·6 days (95% CI 8·3—11·0). 75 (39·6%) of 203 patients recorded that their primary caregivers were absent from work, with a mean duration of 7·3 days (95% CI 5·8—8·7). 74 patients (36·5%) reported spending at least one night in hospital, with a mean stay of 4·2 nights (95% CI 3·3—5·2). 193 patients (95·1%) reported contact with health-care services, with a mean of 4·0 contacts (95% CI 3·7—4·4). 71 (78·0%) of 91 patients reported severe problems due to measles infection on the EQ-5D dimension of health concerning their ability to undertake their usual activities. 24 (26·4%) of 91 patients reported severe problems in the depression or anxiety dimension. Interpretation The HRQoL loss due to measles was greater than we had expected. With a mean duration of infection of 13·8 days, this finding can be interpreted as living with 50% health utility for almost 2 weeks. For context, the mean HRQoL loss for influenza is 0·008 QALYs or 2·92 days. The mean HRQoL loss due to varicella is 0·0027 QALYs or 0·99 days (<15 years old) and 0·0038 QALYs or 1·39 days (≥15 years old). The HRQoL results will inform cost-effectiveness analyses that test new or existing interventions for measles outbreaks.