A study of the genus Scymnus Kugelann (Coleoptera: Coccinellidae) was made based on examination of specimens from various Mexican entomological collections. Twenty-five species were found, of which Scymnus (Pullus) kansanus Casey, Scymnus (Pullus) cerinotum Gordon, Scymnus (Pullus) enochrus Gordon, Scymnus (Pullus) pulvinatus Wingo, Scymnus (Pullus) rohdendorfi Ukrainsky, Scymnus (Pullus) trulla Gordon, Scymnus (Pullus) howdeni Gordon, Scymnus (Pullus) hubbardi Gordon, Scymnus (Pullus) ignarus Gordon, Scymnus (Pullus) impletus Gordon, and Scymnus (Pullus) simillimus Gordon are new country records for Mexico. Two new species are described and illustrated: Scymnus (Pullus) zuritai Nestor-Arriola and Niño-Maldonado, new species and Scymnus (Pullus) erwini Nestor-Arriola and Niño-Maldonado, new species. A key to the Scymnus species occurring in Mexico is provided.