OBJECTIVES: To study the influence of different factors on QOL of patients with partial epilepsy. METHODS: Frequency, severity (NHS3 scale, M. F. O'Donoghue et al., 1996) of seizures and QOL (QOLIE-31 scale, J. Cramer 1998) were analyzed in the population of 242 adult epilepsy patients with partial epilepsy in Moscow. The cross-cultural adaptation of the QOLIE-31 scale was performed. RESULTS: Patients with partial epilepsy who experienced persistent seizures and received ineffective antiepileptic medication had significantly lower total QOL scores than patients receiving optimized therapy: 42.13 ± 4.14 and 48.89 ± 5.45, respectively (ð <0.001). The QOL of patients with partial epilepsy depends on the duration of the disease and severity and frequency of seizures. The severity of seizures has the strongest correlation with subscales of emotional well-being, energy/fatigue, medication effects, and social functioning, whereas the frequency of seizures had the strongest correlation with seizure worry, energy/fatigue, cognitive functioning, and social functioning. After optimized therapy 59% of patients became seizure-free. The QOL of patients receiving optimized therapy depends on their response to the antiepileptic medication. Seizure-free were characterized by improvement in all subscales of QOLIE-31, with a total score of 52.71 ± 3.41. Clinical efficacy/tolerability, QOL improvement, cost-effectiveness parameters were similar on carbamazepine or valproate monotherapy, that supports the use of valproate as adequate first-line drugs in patients with partial epilepsy. Even one or two persistent seizures per year significantly decreased the patient's QOL in comparison to seizure-free patients. CONCLUSIONS: The quality of life of patients with partial epilepsy depends on the duration of the disease and severity and frequency of seizures. Long-term ineffective therapy caused a negative effect on QOL.