The existence of histone H1 has been questioned in Trypanosomatids. We report here the presence of a histone H1 in the chromatin of Trypanosoma cruzi. This protein was purified by narrow-bore reversed phase HPLC and its amino acid composition analyzed and compared with histones H1 from other species. Furthermore, the purified chromosomal protein was digested with proteases and the amino acid sequences of the resulting peptides were analyzed by the automated Edman degradation. The sequences obtained were found to present a high degree of homology when compared to the carboxy terminal domain of other known histones H1.