This paper reviews some of the recent'results obtained regarding electrical recombination at dislocations in Si and Gap using the TEM method and the SEN EBIC and CL methods. The SEM methods have spatial resolutions down to 1 pm, and so electrical and luminescent information can be obtained from individual dislocations. By examining the same areas by TEM and SEM methods, structural, elec- trical and luminescent d ata can be compared. The results indicate that the recombination efficiency is controlled by the d iffusion of carriers to the dislocation for Gap, but by the recombination me- chanism at the dislocation for Si. For Si , marked1 y different recombination efficiencies occur at dissociated and undissociated dislocations.