In article results of research of a chemical structure of humic acids of low-moor woody-grassy type of peat of Tomsk Region are resulted by methods of the elemental analysis and infra-red spectroscopy. In this work results of toxicological research of humic acids also are described: acute toxicity, pathomorphology and flow properties of blood. It is shown, that humic acids of low-moor woody-grassy type of peat represent connection with a high share aliphatic fragments submitted long connected by circuits, have a small degree benzenoid, contain active oxygen and itrogen-containing functional groups (carboxylic, hydroxyl, amides, amino groups). It is established, that humic acids at intragastric introduction are nontoxic substances. At intraperitoneal introduction of lethal dozes, the destruction of animals comes from acute intimate insufficiency, thus the cause of acute infringement hemodynamics can be negative influence of humic acids on flow properties of blood.