We report a study of the coagulation of whole blood by oscillatory shear Fourier transform mechanical spectroscopy. The results include the first identification of the Gel Point of coagulating blood in terms of the Chambon-Winter Gel Point criterion and we show how this may be used as an appropriate basis for detecting the establishment of an incipient clot in samples of human blood. A comparison of this technique with results obtained from a thromboelastograph (TEG) indicate that the latter is not capable of detecting the incipient clot, whose establishment can occur several minutes prior to the first recorded TEG response. Our results also reveal, for the first time, the incipient clot's fractal characteristics. An analysis of the viscoelastic data obtained at the Gel Point of samples of whole blood drawn from healthy individuals indicate that the incipient clot is characterised by a fractal dimension d(f) = 1.74( +/- 0.07). The significance of these findings is discussed in terms of their potential application in studies of pathologically induced changes in blood clot microstructure. (c) 2007 Elsevier B.V. All rights reserved.