The xanthine (caffeine, theobromine and theophylline) content of decoctions of seven Ilex spp. was studied by HPLC using UV and a photodiode-array detector. Ilex paraguariensis (‘Mate’ or ‘Yerba Mate’) is widely used in South America as a tealike beverage and the other six species are used as substitutes or adulterants of it. The results showed that I. paraguariensis has the highest amounts of caffeine and theobromine. Traces of caffeine were detected in I. theezans, I. dumosa, I. microdonta and I. pseudobuxus. Traces of theobromine were detected in I. argentina and I. microdonta. From the seven Ilex species investigated, theophylline was detected in I. theezans, I. dumosa and I. pseudobuxus, but only I. pseudobuxus has quantifiable amounts: 0.6 mg% (6 ppm). © 1998 John Wiley & Sons, Ltd.