Although several methods for isolating genomic DNA from trypanosomatid protozoa exist [1-3], all are time-consuming and cumbersome. Faster, simpler and efficient protocols for preparation of DNA from these protozoa are needed to ease the screening of mutants and transfectants. We describe the use of a bacterial lysis method to isolate chromosomal DNA from a wide range of trypanosomatids. The method is based on the finding reported by He et al. [4], who noticed that phenol/chloroform treatment of Escherichia coli cells in the presence of LiCl and Triton X-100 solubilizes plasmid DNA, while precipitating unwanted chromosomal DNA and denatured cellular proteins. In applying this lysis method to the isolation of episomal DNA from transfected trypanosomatids, we found that, unlike bacterial genomic DNA, chromosomal DNA of trypanosomatids was soluble in the phenol/chloroform/Triton/LiCl mixture. This observation prompted us to use the bacterial lysis method as a routine protocol for extraction of DNA from trypanosomatids. (C) 1993 Elsevier Science B.V. All rights reserved.