BACKGROUND:: During surgery, circulation in the Deep Inferior Epigastric Perforator free flap (DIEP) changes. Although blood flow is an important parameter for surgical outcome, little research has been performed on this topic, especially during the process of transplantation. This study examined the pattern of perfusion of DIEP flaps over time. METHODS:: Sixteen flaps were studied in 14 DIEP patients. With the Laser Doppler Imager, flap perfusion was measured at 4 different time points before, during, and after surgery. RESULTS:: Both central and peripheral perfusion did not alter after dissection, when blood supply became restricted to the abdominal vascular pedicle. After transplantation, blood flow was higher in the central part of the flap compared with the peripheral border. Central flow increased after transplantation, compared with measurements before and during surgery. Peripheral flow, however, decreased after transplantation. CONCLUSIONS:: Surprisingly, flap perfusion did not alter after dissection. It only changed after flap transplantation, when central blood flow increased and peripheral flow decreased.