Chlorine and proton zero‐field NMR has been observed in three new antiferromagnetic materials CsMnCl3·2H2O, KMnCl3·2H2O, and Cs2MnCl4·2H2O. Their Néel temperatures are 4.8, 2.74, and 1.86°K, respectively. In KMnCl3·2H2O and Cs2MnCl4·2H2O at 1°K the chlorine lines lie in the range 6–21 MHz and the proton lines in the range 18–24 MHz. In CsMnCl3·2H2O they lie at half this value. CsMnCl3·2H2O contains linear Mn–Cl–Mn chains and this is apparently reflected in its high Néel temperature compared to Cs2MnCl4·2H2O in which no such chains exist. Presumably the potassium salt also contains such linkages and the Néel temperature and the grouping of the chlorine lines indicate their presence. The transfer hyperfine interactions between the magnanese and chlorines are all approximately equal in these salts, MnCl2·4H2O and Rb2MnCl4·2H2O for which values have been previously reported. The small variations can be accounted for by differences in Mn–Cl distances.