Background: Older patients are now the rule rather than the exception in hemodialysis (HD). Cognitive impairment is common among persons with end stage renal disease (ESRD) and is associated with poor outcomes. Aim: To assess the prevalence of cognitive impairment among older adults on HD and the association of different patients' demographics and characteristics with cognitive impairment. Materials and methods: A cross section study was conducted to assess the cognitive functions of elderly subjects on HD. 94 subjects, 60 years old and above, were included. All subjects were subjected to: 1-comprehensive geriatric assessment. 2-Laboratory investigations including: hemoglobin, serum creatinine, serum urea, serum potassium, serum sodium and serum albumin. Kt/V as a marker of dialysis adequacy was calculated. Results: The study revealed that 26 (27.7%) patients had normal cognitive function, 32 (43%) had mild cognitive impairment, 21 (23%) had mild dementia, 8 (8.5%) had moderate dementia and 7 (7.4%) had severe dementia. Older age, low education level and longer duration of dialysis history were found to have significant associations with cognitive impairment, [P: < 0.001, 0.002, and 0.012 respectively]. While hemoglobin, serum albumin, serum creatinine, serum urea, serum potassium and Kt/V showed no significant association with cognitive impairment, Serum sodium and dry weight dialysis showed significant difference between patients with normal cognitive function and patients with cognitive impairment, [P <0.001 both]. Conclusion: Cognitive impairment is prevalent in Egyptian older adults on HD and more prevalent and severe in those with older age, low education, lower level of serum sodium, longer duration of dialysis history and higher dry weight.