Aim: The CYP2C9 IVS8-109T allele was recently found to be more frequent among Swedish individuals, who have the highest losartan metabolic ratio (MR; losartan:E-3174). Thus, the influence of the CYP2C9 IVS8-109A>T polymorphism on the losartan MR was evaluated among healthy Ecuadorians. In addition, the frequency of the CYP2C9 IVS8-109A>T polymorphism was determined. Results: Among CYP2C9-homozygous wild-types, those with the CYP2C9 IVS8-109T/T versus A/A genotypes had a lower MR (p < 0.05). Furthermore, the frequency of the CYP2C9 IVS8-109T variant was lower in Ecuadorians (21.4%; p < 0.001) than in populations from Sweden or Asia (ranging from 32 to 46%). Conclusion: In this Ecuadorian population, the CYP2C9 IVS8-109T allele was associated with an increased CYP2C9 hydroxylation capacity. Further investigation needs to be carried out in order to clarify the relevance of the SNP of CYP2C9 IVS8-109A>T on losartan hydroxylation across populations and its potential implications in CYP2C9 activity. Original submitted 19 February 2014; Revision submitted 16 May 2014