One of the earliest postulates concerning the physiological basis of flap survival is attributed to Sushruta, who, in his inimitable style, very succinctly noted in Sanskrit verse the following words: "through continuity survives." Sanskrit being a very telegraphic language, what derives from these words is as follows: Through (the flap's) continuity (with its original location) (it) survives. The principle of continuity has survived through the ages, though continuity has come to imply vascular continuity based on the Harvesian model of circulation. No matter how we classify flaps, i.e., random or axial, the Harvesian model of circulation is the key to the mechanism of survival. Lately, however, a new category of flaps, that is, "venous flaps," have been reported by a number of investigators where the classical Harvesian model is not in evidence, at least apparently. The following effort is directed toward presenting the existing data on this subject for future guidance in research and clinical applications.