Meconium samples of 20 healthy full-term babies were analyzed for free fatty acid content. The total fatty acid content per net weight varied by as much as 9-fold between samples. Considerable variability was also observed in the individual fatty acids found in each sample. Palmitic, stearic and oleic acids were the most abundant fatty acids. Significant amounts of arachidonic and linoleic acids were found. Long-chain iso fatty acids, which are rare in mammalian tissue, were found. The source of these fatty acids is unknown, but intestinal lipases and transplacental origins may be important.