Abstract: Cognitive impairment is a replicable feature of Bipolar disorder with measurable changes being present both during episodes and in remission. An observational, cross-sectional clinical study was carried out to study the nature and frequency of cognitive impairment in Euthymic Bipolar Affective Disorder (BPAD) patients. Participants included 40 Euthymic BPAD patients as cases and 40 controls with no history of psychiatric illness. Current mood symptoms were assessed with Young Mania Rating Scale and Hamilton Depression Rating Scale, cognitive functions were assessed by Standardized Mini Mental State Examination (SMMSE), Trail Making Test Part-B (TMT-B) and Digit Symbol Substitution Test (DSST). There was significant difference between cases and controls in number of errors committed and the mean time taken to complete TMT-B and DSST (p<0.01). in within group analysis of cases there was higher mean time taken and more errors were committed in subjects in the age group of 40-60 years, substance use, lower socioeconomic status, lower educational status and longer duration of illness. The degree of cognitive dysfunction in BD increases with each significant mood episode The relationship of cognitive impairment to functional outcome in BD highlights its significance as a treatment target.