Electronic structure calculations using the local-density functional method were shown to accurately reproduce the geometry of five oxo-Tc (V)-based radiopharmaceuticals containing a variety of donor ligands. Calculations were performed using the DGauss program on a Cray C90 supercomputer, requiring approximately 40 CPU h for each molecule. The predicted bond lengths were within +/- 0.04 A of the crystallographic coordinates, and bond angles within +/- 4 degrees. Root mean square (RMS) deviations between the predicted and crystallographic coordinates were less than 0.06, and visual inspection demonstrated nearly perfectly superimpossible structures.