The model of embryonic stem cells from R1 mice at the stage of embryoid bodies was used to study effects of slow clinostatting on neuronal differentiation with the help of two markers--beta-III tubulin (early differentiation) and MAP2 (late differentiation). As compared with the control, the number of beta-III tubulin-positive neurons was found increased and of MAP2-positive neurons--decreased. As regards MAP2- positive neurons, it is concluded that the gravity factors have a specific effect on EB. The beta-III tubulin staining makes possible determination of the total number of neuronal cells at different stages of development. The observed increase in the number of beta-III tubulin-positive neurons may evidence a nonspecific mechanic effect of clinostatting at the EB stage. It was shown that EB cells are particularly sensitive to clinostatting.