The interaction of vacancies with 30° and 90° partial dislocations in silicon is examined. In particular, the structures and binding energies are calculated using hydrogen-terminated clusters and local density-functional theory. Moreover the electronic structure is determined using supercells containing dislocation dipoles. Vacancies are found to have binding energies of approximately 2.0 eV and 0.9 eV to 90° and 30° partials, respectively. The elastic strain field of the partials makes the fourfold vacancy reconstruct, which essentially clears the fundamental gap