Apple pomace (AP) and spent malt grains (SMG) were used as the major substrate components for the production of a high-value fungal oil containing up to 11.43% biologically active gamma-linolenic acid (GLA). The solid-state fermentation (SSF) process developed for GLA production was affected by substrate composition and moisture, agitation and aeration. Under optimised conditions GLA yields as high as 3.50 g/kg moist substrate were obtained from Thm,Thamnidium elegans CCF 1456, grown on a substrate consisting of a mixture of AP and SMG impregnated with peanut oil and a nutrient solution, after 8 days of incubation.