To improve lipid productivity, co-cultivation of Chlorella sp. 114341 and Monoraphidium sp. FXY-10 for lipid production was studied. Compared with mono-cultivations, co-cultivation of the two microalgae significantly increased the accumulation of total biomass and total lipid yield, and enhanced the lipid productivity (29.52 mg L-1 d1). Fatty acid compositions significantly varied in different cultivations. The content of C18 fatty acids in co-cultivation significantly increased, especially for oleic acid (32.45%) and linolenic acid (10.03%) compared with that in mono-cultivation. Moreover, high saturated and monounsaturated fatty acids (55.85%) were obtained in co-cultivation, which suggests their potential as a biodiesel feedstock. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.