The core lipids, polar and non polar lipids, of the novel canthaxanthin-producing archaeon, Haloferax alexandrinus strain TMT. were investigated using thin-layer chromatography (TLC), spectrophotometry, electron ionization-mass spectroscopy (EI-MS), fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic response spectrometry (C-13-NMR) and high performance liquid chromatography (HPLC). This archaeon appeared to contain diphytanyl diether lipids (C-20-C-20) as core lipids. The major phospholipids were found to be phosphatidylglycero-phosphate-methyl ester (PGP-Me) and phosphatidylglycerol (PG), but no phosphatidylglycero-sulfate was detected. The strain contained two glycolipids, sulfated diglycosyl diether (S-DGD-1) and unsulfated diglycosyl diether (DGD). Analysis of the non polar lipids revealed the presence of beta-carotene, 3-hydroxyechinenone, gamma-carotene, cis-astaxanthin, lycopene, trisanhydro-bacterioru-berin, monanhydro-bacterioruberin, bacterioruberin isomer, bacterioruberin and canthaxanthin. Although the polar lipids profile of Hfx. alexandrinus strain TMT was similar to those of other species of the genus Haloferax, the non polar lipid (carotenoids) profile was markedly different. Further experiments on the influence of NaCl concentration on the lipids composition of Hfx alexandrinus strain TMT demonstrated the dependence of the proportion of each of bacterioruberin, beta-carotene and canthaxanthin on the NaCl concentration in the growth media.