Experimental results are presented on the performance of an IR multidither adaptive-optics system with rotating, extended targets. A nine-zone deformable mirror with superimposed dithers was employed at 10.6 mum with spherical metallic targets of varying roughness and diameter. The results presented include openloop discriminants, target speckle-noise spectra, and closed-loop beam quality obtained as functions of target and system parameters. Experimental results are interpreted using a simplified model for the adaptiveoptics system and target.