Brain fatty acid composition in the fetal, full term and postnatal piglet was analyzed. 2. Changes in fatty acid content of developing pig brain parallel those found in the human. 3. Total fatty acids per gram of brain increase with post conceptional age. 4. Brain concentration of long chain derivatives of essential fatty acids, c18:2omega6 and c18:3omega3 increase during gestation while levels of shorter chain precursors (c18:2omega6 and c18:3omega3) remain low. 5. The results indicate that the developing piglet is an appropriate model, analogous to the human, for studies of changes in brain fatty acid content during neural development throughout the perinatal period.