We analyse the most recent experimental data regarding D^0 - \bar{D^0}
mixing, allowing for CP violation. We focus on the dispersive part of the
mixing amplitude, M^D_{12}, which is sensitive to new physics contributions. We
obtain a constraint on the mixing amplitude: |M^D_{12}| < 6.2\times 10^{-11}
MeV at 95% C.L. . This constraint is weaker by a factor of about three than the
one which is obtained when no CP violation is assumed.Comment: 9 pages, revtex4; One reference updated, one reference added,
footnote 3 correcte