We report an increase of negative magnetoresistivity from 1.7% to 9% in the Ba(2)Co(0.5)Zn(0.5)S(3) series (0 <or= x <or= 0.5), derived from Zn(2+)/Co(2+) substitution in Ba(2)CoS(3); Zn(2+) substitution destroys the one-dimensional antiferromagnetic ordering typical of Ba(2)CoS(3), in favour of a paramagnetic behaviour, and considerably increases the value of the resistivity, and to the best of our knowledge Ba(2)Co(0.5)Zn(0.5)S(3) shows the most negative magnetoresistivity among the one-dimensional sulfides (MR approximately 9%).