A low expense process has been developed for recovering esterified eicosapentaenoic acid (EPA) from microalgae and fish oil. Over 70% of the EPA content in the esterified crude extract of microalgae were recovered at purities exceeding 90%. The recovery scheme utilizes either wet or freeze-dried algal biomass. The process consists of three main steps: (1) simultaneous extraction and transesterification of the algal biomass; (2) argentated silica gel column chromatography of the crude extract; and (3) removal of pigments by a second column chromatographic step. Argentated silica gel chromatography recovered about 70% of the EPA ester present in the crude fatty eater mixture of fish oil, but at a reduced purity ( similar to 83% pure) compared to the microalgal-derived EPA. The optimal loading of the fatty ester mixture onto the chromatographic support was about 3% (w/w) but loadings up to 4% did not affect the resolution significantly. The process was scaled up by a factor of nearly 320 by increasing the diameter of the chromatography columns. The elution velocity remained constant. Compared to the green alga Monodus subterraneus, the diatom Phaeodactylum tricornutum had important advantages as a potential commercial producer of EPA. For a microalgal EPA process to be competitive with fish oil derived EPA, P. tricornutum biomass (2.5% w/w EPA) needs to be obtained at less than $5 kg(-1) If the EPA content in the alga is increased to 3.5%, the biomass may command a somewhat higher price. The quality of microalgal EPA compares favorably with that of the fish oil product. Compared to free fatty acid, EPA ester is mon stable in storage. Shelf-life is extended by storing in hexane. The silver contamination in the final purified EPA was negligibly small ( < 210 ppb). (C) 2000 Elsevier Science Ltd. Ail rights reserved.