Phaffia rhodozyma (now Xanthophyllomyces dendrorhous) and Haematococcus pluvialis are known as the major prominent microorganisms able to synthesize astaxanthin natural pigment. Important research efforts have been made to determine optimal conditions for astaxanthin synthesis. When the focus is on astaxanthin production, the maximal reported value of 9.2 mg/g cell is obtained within H. pluvialis grown on BAR medium, under continuous illumination (345 mu mol photon m(-2) s(-1)) and without aeration. Whereas fermentation by mutated R1 yeast grown on coconut milk produced 1,850 mu g/g yeast. However, when looking at astaxanthin productivity, the picture is slightly different. The figures obtained with P. rhodozyma are rather similar to those of H. pluvialis. Maximal reported values are 170 mu g/g yeast per day with a wild yeast strain and 370 mu g/g yeast per day with mutated R1 yeast. In the case of H. pluvialis, maximal values ranged from 290 to 428 mu g/g cell per day depending on the media (BG-11 or BAR), light intensity (177 mu mol photon m(-2) s(-1)), aeration, etc. The main aim of this work was to examine how astaxanthin synthesis, by P. rhodozyma and H. pluvialis, could be compared. The study is based on previous works by the authors where pigment productions have been reported.