The crystal structures of 2,6-dichloroacetanilide, 2,6-Cl2C6H3NHCOCH3, in the low-temperature phase II and high-temperature phase I have been determined at 295 K. [Phase II: C 52h (P21/c); Z= 4; Ï calc= 1.475 Mg m^{â 3}; a= 783.4(2) pm, b= 1531.9(4) pm, c= 897.5(2) pm, β= 121.45(1)°; R W= 0.041. Phase I: D 42(P212121); Z= 4; Ï calc= 1.416 Mg m^{â 3}; a= 1726.8(4) pm, b= 1167.4(3) pm, c= 474.9(2) pm; R W= 0.055.] The molecular geometry is very little influenced by the difference in packing between phase I and phase II. ν(³⁵Cl)=f(T) was determined for both phases from 77 K up to the melting point/transition point. Single-crystal Zeeman split ³⁵Cl n.q.r. investigations at T= 295 K revealed for (³⁵Cl⁽²⁾)II: e ² Ï zz Q h ^{â 1}= 70.435(4)MHz; η= 0.1214(15); for (³⁵Cl⁽⁶⁾)II: e ² Ï zz Q h ^{â 1}= 70.244(4)MHz; η= 0.1031(15); for (³⁵Cl⁽²⁾)I: e ² Ï zz Q h ^{â 1}= 69.674(4)MHz; η= 0.1293(15); for (³⁵Cl⁽⁶⁾)I: e ² Ï zz Q h ^{â 1}= 68.890(4)MHz; η= 0.1307(15). The principal axes Ï (j)zz nearly coincide with the bond directions C^(j)â Cl^(j) in both phases. There is a small widening of the angle [Ï zz(³⁵Cl⁽²⁾), Ï zz(³⁵Cl⁽⁶⁾)] in comparison with the value of the angle (C⁽²⁾â Cl⁽²⁾, C⁽⁶⁾â Cl⁽⁶⁾) of the crystal structure. The influence of the â NHCOCH3 group on η and on the orientation of the axes Ï xx and Ï yy is discussed for both phases and is compared with the results reported for 2,3,6-Cl3C6H2OCOCH3.