Fluorescein angiography (FA) was performed on 83 patients (68 diabetics) with foot ulcer or gangrene. Densitometric measurements were made on the FA images, and different FA parameters were defined. These parameters, as well as systolic ankle and toe blood pressures, were evaluated for predicting the future course, i.e., whether healing would occur or whether major amputation below or above the knee had to be performed. The toe slope (i.e., the rate of increase of fluorescence on the big toe during the first 10 seconds after its appearance on the toe) predicted healing correctly in 0.83 and major amputation in 0.88. The ankle and toe pressures had only slightly lower predictive value. The combination of ankle pressure and toe slope predicted healing correctly in 0.91 and major amputation in 0.88. When ankle pressure cannot be measured, FA is the method of choice. Further, FA provides information on regional blood flow unobtainable by any other method.