OBJECTIVES: Epilepsy has a significant impact on the patient, with higher frequency of seizures being associated with lower quality of life. The association between utility and epilepsy clinical status is less well defined. In this analysis, we present utility values that were collected during a prospective study of patients with intractable epilepsy and describe the association between utility scores and clinical status. METHODS: One hundred twenty-five patients with intractable epilepsy were recruited at a tertiary referral centre in London, UK. At recruitment, each patient was about to start treatment with a new adjunctive anti-epileptic drug (AEDs). Patients were interviewed at baseline, three months and six months. At each visit patients completed a semi-structured interview, the National Hospital seizure severity and frequency scale and the EuroQol EQ-5D. Results are presented for both the EQ-5D tariff and VAS (visual analogue) scores. Clinical response was determined as a 50% or greater reduction in baseline median seizure frequency. RESULTS: At baseline, mean EQ utility score was 0.850, (VAS=65.08). Mean values were lower in patients with higher seizure frequency, with utility scores of 0.798, 0.902 and 0.934 in patients with >10, 2-9 and =1 seizure per month, respectively. VAS scores were 62.85, 66.96 and 70.71 for these groups. At 6 months, 20/125 patients had become seizure-free, with a mean utility value of 0.923 (VAS=77.63), compared with 0.824 (VAS=66.56) in patients who did not achieve a 50% reduction in seizures. The mean utility value of patients who prematurely discontinued treatment (n=50) was 0.846 (VAS=64.89). CONCLUSIONS: More frequent epilepsy seizures were associated with lower utility values in this prospective study of patients with active epilepsy. In addition, patients who became seizure-free on treatment reported higher utility gains than those who failed to respond. Better seizure control may result in utility gains in epilepsy patients.