In response to highly severe environmental conditions, the accumulation of vast levels of astaxanthin by Haematococcus Pluvialis is a recorded event. However, there is little investigation into the nature and possible interactions of the poisonous chemical factors on this pigment's synthesis. In this study, H. pluvialis was exposed to the environment phenol to determine cellular responses, synthesis of pigments, and astaxanthin. The phenol influences in different concentrations (0, 50, 100, and

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... 150 mg l-1) were checked out by two ways; a treatment (14 days) and pre-treatment (7 days + 7 days) done on green and red stages of H. pluvialis. The amount of carotenoid, protein, and dry weight increased, but the amount of carbohydrates and chlorophyll reduced in treated green cells with a phenol. The pre-treatment increased the amount of chlorophyll a, carbohydrates, and carotenoids in green cells, but it did not significantly affect the dry weight, protein of green cells, and the amount of protein in red cells. The phenol treatment also enhanced the carotenoid, carbohydrate, dry weight, and protein of red cells. In general, the treatment and pre-treatment of phenol in the green phase and low concentrations significantly affected the alga. However, the pre-treatment had a more considerable effect on red cells in high concentrations. While the treatment in the high concentrations had notable effects on the xanthophylls, pre-treatment had the same effects on the xanthophylls at low concentrations. These results show that H. pluvialis can adapt to toxic environments due to the xanthophylls.