A developing laminar flow of power-law fluids in the entrance region of curved pipes has been investigated by analyzing the three-dimensional elliptic equation numerically and measuring the velocity distribution with an optical fiber LDV. Flow mechanism from the curved pipe inlet to the fully developed region has been made clear under the condition of power index n>0.6, two curvature radius ratios Rc=10 and 30, and Dean number De=100∼500. As the power index decreases, the primary flow becomes more highly distorted and the axial velocity distribution with double peaks appears on the symmetric plane in the initial development. Also, the secondary flow increases dramatically just after entry and declines rapidly to form another vortex pair in a part of the developing region.