Ionic abundances for two irregular dwarf galaxies belonging to the Local Group, GR 8 and Sextans B, are presented. The oxygen abundances have been found to be 0.055 solar masses and 0.16 solar mass, respectively. The Ne(2+)/O(2+) abundance ratio is within the range of what is observed for other irregular galaxies but the N(+)/O(+) and the S(+)/O(+) ratios are significantly lower. In one of the H II regions observed in GR 8 the helium content is higher than in the others. Two possibilities, pollution of the interstellar medium and a preferential loss of metals by the galaxy, are discussed. Data for both galaxies fit well the total mass-metallicity relation as given by Talent (1980).