The presence of cacao has been discovered in the state of Yucatan, Mexico. Cacao in this region has been mentioned since Prehispanic times by diverse chroniclers and investigators. Nonetheless, until the present, there did not exist concrete evidence of the existence of cacao in this area. Apparently, the climate and soil of Yucatan are not adequate for the natural growth of this species, which requires great humidity throughout the year and deep soils. Cacao was found in three sinkholes (k'o'op) to the south of Valladolid. The trees found are of a rare form of cacao only known in the Lacandon region in Chiapas: Theobroma cacao L. subspecies cacao forma lacandonica Cuatrecasas. A discussion of the importance of this discovery from the perspectives of biology, ecology, and history is presented. This discovery reinforces the importance of the present-day flora for understanding the management of vegetation in the past.