In this Letter NQR frequencies of Cl-35 in some organo-germanium. chlorides are calculated by an ab initio method. The Ge-O distances in structures (1)-(3) (Fig. 1) were varied in the range 1.5-3 Angstrom. After the optimization of the geometry of molecule in each selected distance. the Cl-35 frequencies were calculated (nu(Q)(cal)). Employing the correct value of nu(Q)(cal) leads us to reliable Ge-O distances. All calculations have been carried out with the GAUSSIAN 98 program. The differences between nu(Q)(exp) and nu(Q)(cal) in these structures were chosen as a measure to select the proper Ge-O distance. Our results are in agreement with (XRD) data. (C) 2002 Published by Elsevier Science B.V.