To investigate the extent and nature of the objective and subjective cognitive deficits and health-related quality of life (HRQOL) in adult outpatients with relatively well-controlled partial epilepsy without symptomatic aetiology, who were on carbamazepine (CBZ) monotherapy. Furthermore, we studied the influence of the epilepsy history and medication on various cognitive functions and the HRQOL. 56 outpatients (29 male, 27 female, mean age 41.3 years) with partial epilepsy were compared with 56 age-, gender-, and education-matched healthy controls. Patients were tested on attention, memory, speed of information processing, and executive functioning. Questionnaires aimed at measuring self-perceived cognitive functioning (CFQ) and HRQOL (SF-36) were administered. Mann Whitney-U tests were used to compare the two groups. Linear regression analysis was performed to identify the epilepsy and medication-related factors that are associated with cognitive functioning and HRQOL. Patients scored lower on measures of attention (P = 0.03), learning (P = 0.02) and speed of information processing (P = 0.00). Mental aspects of HRQOL such as fatigue were lower (P = 0.00), whereas physical functioning was unaffected. These patients also expressed reductions in mental functioning as indicated by a low self-perceived cognitive functioning (P = 0.01). Age at onset, duration of epilepsy, seizure type, seizure frequency, localisation, years on CBZ, and CBZ dosage were not related to cognitive functioning or HRQOL. Patients with partial epilepsy, even when able to maintain regular jobs, have impaired cognition and HRQOL that cannot be attributed to their epilepsy history or CBZ dosage or years of CBZ intake. Therefore, physicians should be more aware of their cognition and HRQOL, in addition to the antiepileptic drug regime.