Three hundred and thirty experimental skin wounds were studied by fluorescein dye and microangiographic techniques. Tightly tied sutures frequently produced small avascular areas, but the edges of the entire wound were never devascularized. Changes on the microangiograms were first seen at three days when vasodilatation and an increase in the number and size of the vessels surrounding the wound occurred. Regardless of the type of closure, this vascularization reached a peak at seven days, then slowly receded. New vessels could be seen crossing the wound by five days. Tightly tied sutures produced avascular areas on the angiograms, which corresponded to areas of necrosis seen on histological sections. Unless properly tied, mattress sutures were more likely to produce such microinfarcts than were either simple or continuous ones.