The extent of microvascular damage from frostbite can be accurately demonstrated by vascular microcorrosion casting techniques (P. S. Daum, W. D. Bowers, Jr., J. Tejada, and M. P. Hamlet, Cryobiology 24, 65-73, 1987). In the present investigation, the peripheral vasodilator buflomedil was evaluated for its ability to ameliorate microcirculatory damage from acute experimentally induced freeze injury. This drug has been reported to decrease tissue loss in human frostbite patients when given intravenously during thawing (J. Foray, P. E. Baisse, J. P. Mont, and Cl. Cahen, Sem. Hop. Paris 56, 490-497, 1980). In seven groups of anesthetized rats, left hindpaws were cooled to heat of fusion; cooling continued until the temperature in the footpads fell to -15 degrees C. Prior to cooling, group 1 received a tail vein injection of 1 ml saline/kg, while group 2 received 10 mg buflomedil/kg. Immediately following cooling, group 3 received an injection of 10 mg buflomedil/kg. Hindpaws were rapidly rewarmed in a 40 degree C bath. During rewarming, left hindpaws from group 4 were immersed in deionized water, from group 5 in 24 mg buflomedil in deionized water, from group 6 in 30% dimethyl sulfoxide (Me2SO), and from group 7 in 24 mg buflomedil in 30% Me2SO. Right hindpaws served as controls. Vascular microcorrosion casts were made from left and right hindpaws of all groups. There was no significant difference in mean cast weights when frozen hindpaws of the seven groups were compared, although treatment with buflomedil increased the mean cast weight of control hindpaws from groups 3 and 7. It therefore appears that, in this acute model for frostbite, buflomedil does not improve vascular patency.