  We examine the impact of D-Dbar mixing in the extraction of the angle gamma
of the unitarity triangle with B- ->D(*)K(*)- and B- ->D(*)pi- decays. We point
out that the leading corrections, linear in the small mixing parameters x=Delta
m/Gamma and y=Delta Gamma/2Gamma, depend on how the signal selection efficiency
varies as a function of the D proper time, and we estimate the scale factor in
a simplified case. We note that the charm mixing effect is suppressed in the
GLW method. We discuss the case where the leading corrections become quadratic
in x and y, and we point out some limitations of this scenario. We compute the
bias Delta_gamma when D-Dbar mixing is ignored in the rates of B- ->D(*)K(*)-
but not in the measurement of the D decay parameters. We find |Delta_gamma|<~1
deg for all B- ->D(*)K(*)- decays, limited by the measured value of the strong
phase difference between the b-> u cbar s and b->c ubar s decay amplitudes. The
effect in B- ->D(*)pi- decays cannot be neglected.
