A procedure is described for the extraction of DNA and RNA from solitary and colonial ascidians obtained on the east coast of Australia. Modifications to more established procedures have been made to avoid nuclease digestion, binding to polyphenolic compounds and other less well characterized pigments that interfere with the use of nucleic acids for restriction-enzyme analysis and gene-cloning. Tissue is homogenized in liquid nitrogen to produce a powder which is washed three times in 0.25 M ammonium acetate, pH 5.0, to remove a variety of contaminants. This is followed by lysis and immediate extraction in a number of different phenol/CHC1Jisoamyl alcohol mixtures. Additional steps are similar to those described in previous methods. Extraction of RNA by this procedure precludes the necessity for addition ofribonuclease inhibitors.