Resummed jet rates for $e^{+}{e}^{-}$ annihilation into massive quarks

Expressions for Sudakov form factors for heavy quarks are presented. They are used to construct resummed jet rates for up to four jets in $e^{+}{e}^{-}$ annihilation. The coefficients of leading and next-to-leading logarithmic corrections, mandatory for a combination with higher order matrix elements, are evaluated up to second order in ${\alpha }_s$.