  The nucleon's tensor charges (isovector $g^v_T={\delta}u-{\delta}d$ and
isoscalar $g^s_T={\delta}u+{\delta}d$) are calculated using the QCD sum rules
in the presence of an external tensor field. In addition to the standard quark
and gluon condensates, new condensates described by vacuum susceptibilities are
induced by the external field. The latter contributions to $g^v_T$ and $g^s_T$
are estimated to be small. After deriving some simplifying formulas, a detailed
sum rule analysis yields $g^v_T=1.29 \pm 0.51$ and $g^s_T = 1.37 \pm 0.55$, or
${\delta}u=1.33 \pm 0.53$ and ${\delta}d = 0.04 \pm 0.02$ at the scale of 1
GeV$^2$.
