Docosahexaenoic acid (DHA) is the most abundant long chain polyunsaturated fatty acid in the grey matter of the brain. Although man has the capability of converting dietary linolenic acid into DHA, the evidence suggests that this process is slow. Consequently, at the time of most rapid brain development in the first few months of life, there is a critical demand for dietary DHA. Although DHA is provided to a nursing infant from mother's milk, most infant formulas are severely deficient in DHA. Attempts at supplementing infant formulas with fish oils have led to rejection due to the strong fishey odor and taste and high levels of eicosapentaenoic acid (EPA). Consequently, there is a need for an alternative DHA- containing oil as a nutritional supplement for infant formulations, and there is a need for further research on the uptake and metabolism of dietary DHA by both nursing mother and infant. During Phase I we identified a microalgal strain (MK8805) which could grow in a conventional fermenter and produced an oil rich in DHA (30-40%) and deficient in EPA. Our Phase II activities will concentrate on further optimization of the DHA oil production from this organism, development of new methods for oil extraction and recovery, and an initial toxicological assessment of the oil.