Using scanning electronic microscopy of peripheral blood platelets in 32 patients with amyotrophic lateral sclerosis (ALS) and 6 patients with multiple sclerosis (MS), platelets activation, emerging in pseudopodiums formation, aggregation and lysis, was found. Platelets activation was more pronounced in ALS than in MS. It was most markedly seen for quantitative evaluation of the above traits. The features of platelet activation found in the study support the evidence for considering ALS as a systemic disorder being characterized by a broad spectrum of alterations of biological processes.