We investigated the effects of inositols, which are well-known plant growth-promoting agents, on the growth of the oceanic microalga Dunaliella salina. Of the four inositol derivatives tested (myo-inositol, scyllo-inositol, D-chiro-inositol, and L-chiro-inositol), myoinositol (MI) showed the greatest growth-promoting effect in a concentration-dependent manner. The yield of biomass from the alga cultured with 500 mg L-1 of MI was 1.48-times that of the control culture. No significant effect of MI on the total carotenoid content was observed, but neutral lipid content was significantly increased, 1.34-times greater than the control. MI also influenced the fatty acid methyl ester composition, with the levels of linoleic, linolenic, and linolelaidic acids significantly higher than those of the control culture. To the best of our knowledge, this is the first demonstration that MI promotes the growth of a marine microalga. Our results suggest that MI has potential for enhancing the efficiency of biofuel production by D. salina through growth promotion and increasing lipid productivity. (C) 2014 Elsevier Ltd. All rights reserved.