The assessment of melatonin secretion in 25 men and serum butyrylcholinesterase level in 40 patients was performed in acute period of stroke. The interaction between these parameters and cognitive state was analyzed. The low levels of 6-sulfatoxymelatonin in daily urine and butyrylcholinesterase in blood were revealed. The 6-sulfatoxymelatonin level in daily urine < 4,0 ng/ml can be regarded as a potential biological marker of poststoke memory dysfunction. The serum butyrylcholinesterase level < 7,0 nmol/sec-l can be regarded as a potential biochemical marker of the multifunctional type of poststoke cognitive impairment.