We establish the Alexandroff-Bakelman-Pucci estimate, the Harnack inequality, and the Holder continuity of solutions to degenerate parabolic equations of the non-divergence form Lu := xa(11)u(xx) + 2rootxa(12)u(xy) + a(22)u(yy) + b(1)u(x) + b(2)u(y) - u(t) = g (*) on x greater than or equal to 0, with bounded measurable coefficients. We also establish similar regularity results in the corresponding elliptic case. (C) 2002 Published by Elsevier Science (USA).