The flash radiography combining a low impedance high intensity flash x-ray generator and a digital radiography system for biomedical use is described. This flash x-ray generator was a single shot type and consisted of the following essential components: a high voltage generator, a low impedance transmission line using an oil condenser of 120kV-0.15pF, a high speed impulse switching system with a time resolution of less than 1ps, and a new type of x-ray tube having two sets of electrodes. This source could be used for condenser charging voltages of 50 to 120kV and peak currents of 20 to 40kA. The maximum intensities for the Type A and B electrode combinations were about 20 and 40C/kg at lm/pulse, respectively. The exposure times were about fps . The optimum output corresponding to the optimum x-ray quality could be controlled. The peak intensity of the spectrum distribution varied from a low to high photon energy region, and the energy latitude of this spectrum also varied from narrow to wide. The size of the effective focal spot ranged from 0.2 to 3.0mm in diameter. Various kinds of biomedical flash radiography (e. g., the continuous delayed imaging, and image analysis equivalent to the three dimensional image analysis) were accomplished by controlling the source conditions concerning the x-ray intensity, the quality, the spectrum distribution, the effective focal spot, and the delay time.