A novel procedure for measuring the concentrations of lithium and beryllium in different inorganic and biological samples has been studied using18O heavy-ion activation analysis. The specific reactions,7Li(18O,n)2cF and9Be(180,2)19O, are sensitive and selective if the bombardment energy is 25-MeV18O4+. The detection limits for non-destructive analyses are 10 ng Li and 2 ng Be for a 100-second cyclic irradiation. The technique has been tested by analyzing NBS reference materials. It can be applied to a large range of solid samples.