The Baja California peninsula is inhabited by 116 native amphibians and reptiles. The Cape Region, located at the southern end of the peninsula, is one of the main areas of endemism, especially for reptiles. Comprehensive knowledge is lacking for any one specific region of the peninsula, including the Sierra Las Cacachilas, located in the northern portion of the Cape Region. We are evaluating the ... [Show full abstract] amphibian and reptiles diversity by samplings every two months starting from November 2013 to the present. Surveys use pit-fall trap arrays, visual plots surveys, and incidental observations. To date, we have found a total of 33 species (2 amphibians and 31 reptiles) belonging to 27 genera and 12 families. The highest richness was registered for lizards with 16 species, followed by the snakes with 15 species. The most abundant lizard species were: Aspidoscelis hyperythra, Uta stansburiana, Urosaurus nigricaudus, and Callisaurus draconoides. The relative abundance varied seasonally, with the highest observation numbers in July (n=718). Four species (Sauromalus ater, Sceloporus licki, Elgaria paucicarinata, and Masticophis aurigulus) represent new records for the area and range extensions. Of the total species recorded, 41.2% are peninsular endemics and 53% are listed in the mexican NOM-059-ECOL-2010.