A three-dimensional (3D) clinostat is a device for generating multidirectional G force, resulting in an environment with an average of 10(-3)G. We cultured human malignant glioma cell lines in a 3D-clinostat (CL group) and examined the growth properties and chemosensitivity of the cells compared to cells cultured under normal 1G conditions (C group). The growth rate was significantly inhibited in the CL group, but without cell cycle change. Mitochondrial activity was also inhibited in the CL group. Thus, inhibition of malignant glioma proliferation occurred that could be attributed to deceleration of mitosis. Chemosensitivity to cisplatin (cis-diamminedichloroplatinum(II), CDDP) in the CL group was significantly enhanced compared to the C group. This method has significant potential as a treatment of malignant gliomas and a tool for understanding developmental biology.