Currently, many monovarietal vineyards present a minority of mixed cultivars. Some of these cultivars are unknown and could represent an opportunity to discover new and potentially useful genotypes both for research and production purposes. In a 'Carmenère' vineyard planted in 1994 in Palmilla (Colchagua Valley, Chile), a minority presence of other cultivars was found. The present work covers for the first time the identification and characterization of one of these cultivars, which presented a very poor fruit set. Through classic ampelography, it was not possible to associate the studied cultivar with any known cultivar in Chile. However, through a simple sequence repeats (SSR) comparison against the database of the INRA Germplasm Repository "Domaine de Vassal" in France, the cultivar was identified as a triploid accession named 'Folle Blanche Faux' (Vitis vinifera L.) that was previously found in Chile during the season of 1950-1951. This cultivar presents earlier bud breaking than 'Carmenère', has morphologically complete flowers, and shows a physiological disorder around the fruit set, leading to partial or complete bunch necrosis under the environmental conditions of Palmilla. This cultivar contributes to the genotypic richness present in Chile and might be an interesting tool for physiological and molecular studies. It also could become productive under other environmental conditions (i.e., environmental conditions that favor a good fruit set) or by the application of adequate vineyard practices, such as cane girdling at bloom time.