Plectranthus hijazensis Abdel Khalik (Lamiaceae) is described as a new species from Al-Baha Province in Saudi Arabia. Information given on the new species includes a taxonomic description and its affinity to Plectranthus asirensis L. A key to Plectranthus species of Saudi Arabia is provided, and the relationships of the species and the relevant morphological characters, particularly seed, pollen grains, trichomes, and anatomy of stem and leaf, are discussed. A distribution map of the new species and related species is provided.