The conventional finite difference time domain (FDTD) algorithm for solving electromagnetic scattering problems, which uses a uniform Cartesian grid for enmeshing the problem domain, is limited in its ability to model scatterers of arbitrary shapes. In this paper, we extend the FDTD algorithm to a general obliquely Cartesian coordinate system, and apply it in conjunction with an edge-type absorbing boundary condition (ABC) to solve a number of representative TM scattering problems. In addition to extending the FDTD algorithm to obliquely Cartesian grids, we also derive the stability condition for the twodimensional obliquely Cartesian FDTD algorithm.