The molecular structure of (dichloromethyl)-trichlorosilane has been determined by gas phase electron diffraction. It has been found that the effective structure of the molecule has C 1 -symmetry with an angle of rotation τ and a tilt angle ψ of the SiCl 3 -group. Several vibrational amplitudes were fixed at values calculated from transferred Urey-Bradly force constants. Systematic errors resulting from the uncertainties of the fixed parameters have been calculated applying the rules of error propagation. The most important structural parameters (r g in Å, angles in degrees) are: r(Si-C) = 1.905(10), r(Si-Cl) = 2.019(1), r(C-Cl) = 1.774(4), r(C-H) = 1.16(4), ∢ (C-Si-Cl) = 109.8(3), ∢(Si-C-Cl) = 111.4(8), ψ= 4.1(1.0), τ= 6.7(1.4) (the errors in parenthesis include the systematic contributions). Comparison is made with structural data of other representatives of the series CH 3-m Cl m SiCl 3 (m = 0, 1, 2, 3).