A numerical study is performed on entropy generation in L-shaped curved channel for constant wall temperature boundary condition and fully developed laminar flow. An elliptic Fortran program based on SIMPLE algorithm is used to solve continuity, Navier-Stokes and energy equations. The results including local entropy generations due to the fluid frictional and heat transfer irreversibilities, the variations of average entropy generations, average irreversibility distribution ratio and average Bejan number are presented depending on Dean number, aspect ratio and channel orientation. It is concluded that entropy generation due to the heat transfer irreversibility is highly dominant and entropy generation created by fluid frictional irreversibility can be neglected in L-shaped curved channel. Also, it is seen that centrifugal force resulting from curvature strongly affects the entropy generations due to both fluid frictional and heat transfer irreversibilities.