Background: to appreciate physical loads' influence on rising intravascular thrombocytes' activity of healthy mice during the second year of their age. The investigation was fulfilled on 93 healthy males of mice taken into research at the age of 12 months. 45 of them formed an experimental group - they experienced during a year daily physical loads. The control group was composed of 48 healthy males who lived in usual vivarium conditions and didn't experience physical loads. There were applied the following methods of investigation: biochemical, hematological and statistical. Mice under control while growing up were found to have gradual rise of intravascular thrombocytes' activity. Regular daily physical loads between 12 and 24 months of life suppressed the rise of investigated mice' intravascular thrombocytes' activity connected with age. Regular physical loads are able to suppress in case of mice of the 2nd year of life rising with age inclination to the increase of thrombocyte aggregate formation in their blood.