Quadrupolar perturbed l 3 5 Cl NMR spectra are measured in the high-temperature normal (N) phase and in the low-temperature (LT) phase of betaine calciumchloride dihydrate (BCCD) single crystals. The electric field gradient (EFG) tensors at the chlorine sites are precisely determined for both phases. In the N phase, the symmetry of the tensors is in agreement with the space group Pnma known from X-ray studies. The symmetry of the tensors in the LT phase allows to exclude the P11a symmetry proposed previously and confirms the space group Pn2 1 a derived theoretically on the assumption that one order parameter drives the phase transitions in BCCD.