For various pairs of neutral π-systems and their corresponding di- or tetra-anions, a relationship between the 13C n.m.r. chemical shift/charge ratio (KC) and the altered 1H ring current anisotropy is observed. Thus for a 4nπ anion system, the 13C shift sensitivity to charge is significantly lower than the KC value obtained for a diatropic anion. This is explained in terms of the average electronic excitation energy, which influences both the 13C chemical shifts and the ring current intensities. An empirical model which describes the 13C shifts on the basis of a charge term and an anisotropy term is postulated. The anisotropy term is shown to be linearly related to the 1H ring current anisotropy.