Two ^<35>Cl resonance frequecies were measured as a function of temperature ranging from 77 to 320 K for 2,6-dichlorobenzaldehyde. The frequencies of the lines were 34.974 and 35.754 MHz at 298 K. An analysis of the Zeeman effect on the lines using a single crystal revealed that the crystal belongs to the monoclinic system. The angle between the C-Cl bonds belonging to a molecule was estimated to be 128.98±0.01° on the basis of the directions of the efg axes. NQR parameters (|e^2Qqh^<-1>|=67.82 MHz;η=0.01) and (71.24 MHz;0.15) were obtained, respectively, for the lower-frequency line and the higher-frequency one. The resonance lines were assigned with the aid of semi-empirical MO calculations. The orientations of the efg axes were explained on the basis of intramolecular interaction between the Cl atoms and the CHO group.