Platelet serotonin content in patients in the acute period of stroke is an important index of clinical changes during the post stroke period as well as a predictor of development of mental disorders. We studied the association between two polymorphisms (5-HTTLPR and Val66Met BDNF) and the platelet serotonin content in 47 patients with stroke. We also investigated the moderating effect of genetic variants on the association between platelet serotonin content and development of affective and anxiety disorders in stroke patients in the acute period of stroke. The interaction effect of two polymorphisms on levels of platelet serotonin was found. The lowest level was observed in patients with the diplotype LL*ValVal, the highest level--in the group of patients with the LL genotype and genotypes containing at least one copy of a Met allele. No moderating effect of genetic variants on the relationship between serotonin content and affective or anxiety disorder was found.