Electronic and e.s.r. spectra have been measured for the compounds MnL4X2(L =γ-picoline, X = Cl, Br, I, NCS; L =β-picoline, X = Cl, Br; L = 3,5-lutidine, X = Cl, Br, I; L = 3-ethylpyridine, X = Br; L = 3-bromopyridine, X = I, NCS; and L = 3,5-dichloropyridine, X = I), and for some complexes MnL2X2 with the same neutral ligands. The e.s.r. spectra of most of the 4:1 complexes show absorption away from geff= 2, and are interpreted in terms of the zero-field splitting parameters D and λ. The compounds have essentially axial symmetry, with D in the range 0·035 to 0·87 cm–1, and λ close to zero.