The authors present CCD UBV photometry of 142 resolved stars in the Local Group dwarf irregular galaxy GR 8. Its distance modulus has been found to be 25.0. The luminosity function has been derived. The percentage of the total luminosity in stars brighter than MV = -2 is found to be about 30%. The derived differential (IMF) for stars with masses between 3 and 15 M_sun; has a slope of -1.8, larger than those of other Local Group galaxies. To account for the metallicity of GR 8, adopted to be of 0.05 solar, metal enriched gas loss is required, probably together with a low upper mass limit in the IMF. A bimodal IMF, a decreasing SFR or a combination of both is also required to account for the total mass contained into stars and stellar remnants. In this context, a star formation burst mode is necessary to explain the blue colours of GR 8.