Upstream open reading frames (uORF) are small open reading frames located in the 5' untranslated region (5' utr) of a mature mRNA. We analysed in four strains representing the Trypanosoma cruzi groups Tc I, Tc II, Tc IV and Tc VI the uORF present in 5' utr sequences of four genes: P-type H+-ATPase 1, DEAD/H RNA helicase, casein kinase 1.1 and ferredoxin-NADP+ reductase. A segment in the 5' utr at each of these genes encompassing one or more uORF was PCR amplified and sequenced. An analysis of these sequences reveals that the uORF in T. cruzi show minor variations; however, these nucleotide substitutions mirror the divergence of T. cruzi strains into major groups.2030-01-01