Abstract: This invention discloses a cyclic process for the production of astaxanthin rich biomass by cultivating Haematococcus algae. Modified nutrient medium containing 4 nitrogen sources is used for culturing the algae. Green motile cells produced are converted into dormant red cysts which are chilled and stressed for vigorous multiplication. Nutrients are added gradually and the initial germination is carried out without carbon dioxide sparging. The dilution stage is also effected in the absence of carbon dioxide. The stressed red cysts are regerminated and the cycle repeated to produce a biomass enriched with astaxanthin.