Heat shock protein (HSP) 10 is a member of the highly conserved group of molecular chaperons, which are necessary for efficient folding of many proteins in normal and stress conditions and have been implicated in several human diseases. We have characterized the HSP10 genes of Trypanosoma cruzi, the causative agent of Chagas' disease. After sequence analysis of clones obtained from the T. cruzi Genome Initiative, we show that the T. cruzi HSP10 coding region is 300 bp long, encoding a polypeptide of 100 amino acids with highest sequence identity (83%) to HSP10 of Trypanosoma brucei and lowest (28%) to HSP10 of Escherichia coli. The T. cruzi HSP10 genes are arranged in 3 tandemly repeated copies, which give rise to a major mRNA of 1.0 kb that remains unaltered during heat shock; a smaller mRNA species is induced at 37 degrees C by alternate polyadenylation. Finally, the presence of a conserved 5-amino acid residue deletion in trypanosomatid HSP10s led us to generate a molecular model of the T. cruzi HSP10 structure. The oligomeric assembly of this model shows some peculiar characteristics that may have functional significance.