To determine the ingestion and absorption of lipid emulsions, spat were fed algae deficient in stigmasterol and cholesterol and an emulsion containing these two sterols. The ingestion-absorption of the emulsion was estimated by measuring incorporation of these two sterols in oyster lipids during the 33-day feeding period. They were supplemented with 0%, 3%, 10% and 20% emulsion wet weight of the algae dry weight. The results showed that after only 7 days of emulsion supplementation, significant differences were observed in the sterol composition. The quantities of stigmasterol and cholesterol absorbed by the spat were time- and dose-dependent. Nevertheless, compared to algal sterols, the absorption rate of the sterols from the emulsion was quite low and decreased with an increasing supply of emulsion. Other emulsion formulations need to be tested to improve the emulsion absorption rate in oyster spat. However, the sterols appeared to be good markers for assessment of lipophilic artificial diet digestion and absorption. (C) 2000 Elsevier Science B.V.