The aerial parts of several Haplopappus species (Asteraceae), known under the common name "baylahuen", are used as herbal teas in Chile and Argentina. In Chile, "baylahuen" comprises H. multifolius, H. taeda, H. baylahuen and H. rigidus. Little is known about the chemical identity of the infusion constituents in spite of widespread consumption. The aim of the present work was the characterization of phenolics occurring in the infusions and methanol extracts of "baylahuen" by HPLC-DAD-ESI-MS. A simple HPLC-DAD-ESI-MS method was developed for the fast identification and differentiation of Haplopappus spp. used as a tea source, based on the phenolics from the tea and methanol extracts. Some 27 phenolics were tentatively identified in the infusions and methanol extract, including 10 caffeoyl quinic and feruloyl quinic acid derivatives and 17 flavonoids. The HPLC patterns of the Haplopappus tea and methanol extract allow a clear differentiation at the species level. The occurrence of hydroxycinnamic acid derivatives and flavonoids can explain the reputed nutraceutical and health beneficial properties of this herbal tea.