Oleaginous fungi from the genus Mortierella have been used for production of lipids rich in polyunsaturated fatty acids (PUFAs). The major PUFAs produced by fungi are c-linolenic acid (GLA- C18:3 x-6), dihomo-c-linolenic acid (DHGLA- C20:3 x-6), arachidonic acid (ARA- C20:4 x-6), and docosahexaenoic acid (DHA- C22:3 x-3).