The ³⁵Cl NQR resonance frequencies, in MHz, and asymmetry parameters are, for PCl₃: 26.1032, n=0.066+.008; 26.1998, n=0.067+.005 (two equivalent chlorines), and for AsCl₃: 24.9581, n=0.077+.008; 25.0567, n=0.071+.006; 25.4036, n=0.075+.006. Angles between the field gradient Z axes are close to the bond angles determined by X-ray crystallography. A doublet splitting in the spectrum of PCl₃ is ascribed to the effect of ³¹P-³⁵Cl dipole-dipole coupling together with an isotropic coupling of -0.3 kHz.