Antioxidants in plants and their by-products are becoming of increasing relevance, given their detrimental effect on oxidative stress and the ailments therein derived, such as cardiovascular disorders and cancer. Wine, especially red wine, contains flavonols, and moreover, recently foreign literature has recognized the comparatively high levels that Chilean wines possess. As a consequence, it is of interest to classify and evaluate the potential productive concentrations of the flavonols: myricetin and quercetin in Chilean grapes, which pass into the must during the production process. To meet this objective, wine grape samples of Carmenère, Pinot noir, Cabernet Sauvignon, Merlot and Chardonnay were collected in the Casablanca Valley in the 1999 harvest, using a completely randomized design with four repetitions, where each repetition corresponded to a bunch. The proportion of berry skin was determined, and the skins were lyophilised and processed using hydrolysis in the Biochemistry and Vegetable Physiology Laboratory of the La Platina Regional Research Center. Flavonols were measured by high performance liquid chromatography (HPLC) and expressed as mg kg-1 of fruit. According to the results of the study, Cabernet Sauvignon and Carmenère varieties had the highest concentrations of flavonols in the fruit; followed sequentially by Merlot, Chardonnay and Pinot noir. These values are consistent with those reported by other authors in the same wine varieties.