The dipole moments of trinmethylsilanol, triphonylsilanol, dimethylsilandiol and diphenylsilan diol have been determined by the solution method in dioxane, and the results are 1.63, 1.61, 1.94, and 1.74D rtspectively.The experimental data were treated according to tha method of Guagenh)im.For comparison, the dipole moments were also evaluated according to the procedure of Halverstadt and Kumler which gave higher values than Uuggenheim.nwments; and the deviation increases with the number of phenyl groups in the molecule, apparently resulted from the neglect of atomic polarisation.