['Total blood homocysteine (Hcys) and folate levels have been investigated in association with cognitive dysfunction in healthy but not in multimorbid elderly patients. We hypothesized that total serum Hcys is an adequate marker to identify multimorbid elderly patients with cognitive dysfunction assessed by the Short Cognitive Performance Test (SKT) and Mini-Mental State Examination (MMSE).', 'Cross-sectional study.', 'The study center was an acute geriatric hospital.', 'A total of 189 multimorbid elderly patients were recruited.', 'Cognitive dysfunction was determined according to the SKT and MMSE. Biochemical parameters (Hcys, folate, vitamin B12, hemoglobin), nutritional status (BMI, Mini Nutritional Assessment, nutritional intake), and activities of daily living were assessed.', 'According to the SKT, 25.4% of patients showed no cerebral cognitive dysfunction, 21.2% had suspected incipient cognitive dysfunction, 12.7% showed mild cognitive dysfunction, 9.0% had moderate cognitive dysfunction, and 31.7% of patients were demented. The median plasma Hcys value was elevated by approximately 20% in multimorbid elderly patients, independent of cognitive dysfunction. Serum folate and vitamin B12 concentrations were within normal ranges. We did not find significant differences in nutritional status, activities of daily living, numbers of diseases or medications, or selected biochemical parameters between the SKT groups.'] Do total serum homocysteine levels identify cognitive dysfunction in multimorbid elderly patients?