As the first step towards solving the taxonomic problems in the genus Sanchezia (Acanthaceae), neglected for more than 50 years, new synonymies are proposed in this study. Based on an extensive morphological revision, 11 names are synonymized, as follows: S. stenomacra under S. aurea ; S. cyathibractea under S. macrocnemis ; S. bicolor , S. flava , S. megalia and S. speciosa under S. oblonga ; S. capitata and S. stenantha under S. ovata ; S. lutea under S. parviflora ; S. skutchii under S. putumayensis ; and S. arborea and S. decora under S. scandens . With these nomenclatural changes, the number of accepted names within Sanchezia decreases from 55 to 44. Lectotypes are designated for Ancylogyne macrocnemis and S. ovata. Diagnostic characters are provided to identify the treated species, and their taxonomic problems are discussed, highlighting the need for a taxonomic revision of the genus.