AbstractLong chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) are essential for the regulation of critical biological functions in humans and other mammals. EPA production via solid state fermentation of sunflower press cake was investigated using eight fungal strains representing the genus Mortierella. During this study the effect of supplementing the sunflower press cake substrate with 10% (w/w) linseed oil was studied with regard to the supplement’s impact on EPA production and the polyunsaturated fatty acid profile of the fermented substrate. The addition of the linseed oil improved the EPA yield of most strains, leading to a reduction in the average arachidonic acid:EPA ratio from 50.68 to 3.66. The ratio of polyunsaturated to saturated fatty acids was increased significantly (t=5.75, p=0.05) by the addition of linseed oil, with higher desaturation levels among the 20-carbon fatty acids. The strains that produced the highest levels of EPA on sunflower press cake supplemented with linseed oil were Mortierella alpina Mo 46 and Mortierella basiparvispora Mo 88, which produced 6.4 mg and 5.8 mg EPA per g of sunflower press cake, respectively.