Alterations in the cutaneous vasomotion function caused by scald burns to a large area on the flank were observed and quantified in a dorsal skin flap window with a hamster model. Subsequent to chronic implantation of the window chamber to provide direct microscopic observation of blood flow for an entire thickness of skin, control measurements of vasoactivity in a defined network of arterioles were taken by means of a digital video image splitter over a period of several days. A 100° C, 5-second water scald was then effected over 17% to 55% of the total body surface area, and the vasoactivity was remeasured in the targeted set of sites at serial time intervals for 2 to 4 days. Data were acquired directly into a computer and analyzed for both the magnitude and time pattern of diameter fluctuations during 3-minute observation periods. Average and standard deviations of diameters were computed, and the Prony power spectral analysis method was applied to identify the presence and strength of fluctuation frequencies. In general, vasomotion was suppressed for several hours subsequent to the burn, and the activity was dominated by much slower contractions than control. No direction of vessel diameter changes prevailed uniformly throughout the peripheral microcirculation. Large alternate constrictions and dilations were also observed for some arteriolar and venular components, but others exhibited no significant change at all. The incidence and magnitude of peripheral microvascular response was proportional to the size of the injured area.