We derive the two-loop corrections to Bhabha scattering from heavy fermions using dispersion relations. The double-box contributions are expressed by three kernel functions. Convoluting the perturbative kernels with fermionic threshold functions or with hadronic data allows to determine numerical results for small electron mass m_e, combined with arbitrary values of the fermion mass m_f in the loop, m_e²\ll s,t,m_f², or with hadronic insertions. We present numerical results for m_f = m_\mu , m_\tau , m_top at typical small- and large-angle kinematics ranging from 1 GeV to 500 GeV.

PACS numbers: 12.38.Bx