Guarana (Paullinia cupana Kunth) is a Brazilian commodity well known to stimulate human metabolism due to its alkaloid components (mainly caffeine rich) and is used as an ingredient in the beverage industries. Moreover, the processed form (powdered guarana), may have similarities to other products (coffee, tea and cocoa) regarding its effects on ochratoxin A. This study was to evaluate the effect of the alkaloids of powdered guarana on the OTA production and the toxigenic fungal strains presence, with the specific aim of preventing risks to the consumers and to provide scientific data for those involved in the guarana productions chain. The ochratoxin A levels production of guarana were below the method of LOQ (0.50 µg/kg) and the presence of toxigenic strains was observed only in 2% of the samples. The average level of caffeine was 2.6% (minimum 1.8%; maximum 2.9%) and tannins of 14.7% (minimum 10.0%; maximum 23.1%). The effects of alkaloids from guarana on OTA levels and fungal strains was studied and despite the toxigenic strains were observed in guarana, the OTA levels were below the LOQ (2.0 µg/kg), probably due to the high caffeine content fungi inhibition properties.