The mesenteric microvasculature was observed before and after a distant full-thickness cutaneous burn in rats. Diameters, flow velocities, and white blood cell sticking and emigration were measured. Between 30 and 360 minutes postburn 13 to 16 WBC's were found to stick to the venular walls which had an area of 1.57 x 10(4) microns(2). Therefore, the number of WBC's emigrating from the vascular compartment during the 6-hour observation period could be as many as 0.51 X 10(9)/kg. Based on known values for total stores of WBC's, the data suggest that granulocyte sticking and emigration could account for a consumption of granulocytes that on an acute basis could deplete the body stores, which could explain the apparent decrease in total body granulocytes seen clinically following major thermal trauma.