In bipolar patients, neuropsychological and biochemical disturbances persist into the remission period. Excellent lithium responders (ELRs) comprise around one third of lithium-treated patients and have total remission of recurrences on lithium monotherapy. The objective of the study was to assess the performance on neuropsychological tests and to measure brain-derived neurotrophic factor (BDNF) plasma levels in ELRs compared to patients where the effect of lithium was not optimal, and with matched healthy control subjects. The study was performed with 60 patients on prophylactic lithium treatment, 13 of whom were ELRs, and with 60 matched healthy controls. Neuropsychological tests from the CANTAB battery measuring spatial working memory and sustained attention were used. ELRs performed better on all neuropsychological tests, and had higher plasma BDNF levels than the remaining lithium patients but not different from those of healthy controls. ELRs may constitute a specific subgroup of bipolar patients in which long-term lithium administration can produce complete normality.