Because they have demonstrated very high visibility accuracies and have greatly simplified conventional interferometric recombination devices, single-mode fibers are being seriously considered in several optical interferometry projects. This paper deals with light coupling into single-mode fibers. An analytical expression of the coupling efficiency is derived for the monochromatic case. Then, the effect of purely static aberrations is considered. Finally, coupling in the presence of atmospheric turbulence is investigated for long exposure times. Using temporal sequencies of turbulent wavefronts, simulations are performed for a wide range of seeing conditions with both uncorrected turbulence and various levels of correction by an adaptive optics system.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.