A liquid fuel composition for a spark ignition internal combustion engine comprising (a) gasoline blending components, (b) Fischer-Tropsch derived naphtha at a level of up to 50% v/v and (c) oxygenated hydrocarbon at a level less than 50% v/v. While the low octane number of Fischer-Tropsch derived naphtha would normally severely restrict its blendability in gasoline to low levels, it has now been found that Fischer-Tropsch derived naphtha can be included in, for example, ethanol-containing gasoline fuel compositions, in surprisingly and significantly high blend ratios of Fischer-Tropsch derived naphtha to ethanol.