Objective: Multiple sectional studies indicate that the cognitive functions of bipolar disorder (BD) patients in remission are damaged. These studies also suggest that cognitive functions get worse over time. Although the results are inconsistent, there are limited follow-up studies that reveal any contradictory results. Interestingly, there have been major difficulties in the interpretation related to this subject. In particular, scarcity of longitudinal studies and not eliminating the role of multidrug side effects on cognitive functions are just a few. Due to these aforementioned limitations, the longitudinal course of cognitive functions and their sectional differences were investigated in BD patients that underwent remission with monotherapy in this study.