Fatty acids are part of the structural matrix of cellular and subcellular membranes. Alterations in tissue fatty acid composition can affect nerve tissue function by altering membrane thickness or by changing properties of the lipid phase. In this study, the appearance of specific neurodevelopment responses was observed on rap pups whose dams were fed on varied dietary fatty acid composition. Three dietary treatments of corn oil, fish oil and reference meals were administered on these groups of pregnant dams. From postnatal day 5 to 30, littered pups were assessed daily for the appearance of neurodevelopmental reflexes based on the Smart- Dobbing method. The neurodevelopmental attributes of Righting reflex, Cliff avoidance, Negative geotaxis, Auditory startle, Vibrissa placing, Free-fall righting and Visual placing was observed in experimental pups between day 5 and 30. Tests were conducted between 1200 and 1400h. A 30 seconds time limit was employed in testing of the cliff-avoidance and negative-geotaxis appearance. The time appearance of auditory-startle and vibrissa-placing responses were significantly delayed (P and lt;0.05) in pups of dietary fish oil and ndash; fed dams than those of corn oil fed dams. The delay in auditory-startle response may be due to negative myelination of the auditory brainstem pathway.