In the 21-d dry immersion (DI) study, the sensorimotor evaluation of illusions was tested by "grasping" neutral 3D objects and also objects provoking the Ponzo and Muller-Lyer visual illusions. Ten human subjects were tested before DI, on DI days 3, 10 and 20, and after DI completion. The pre-DI strength of Muller-Lyer illusions adjusted to match the neutral stimulus evaluation was above the zero, whereas the Ponzo illusions strength was virtually same. The adjusted illusions strength tended down at the DI onset, recovered by DI day-10 and degraded again. These results are in a good agreement with the sensorimotor data of the tracking test performed in a 5-d DI study and support the hypothesis that gravitational unloading affects the dorsal stream of visual processing.