The effect of inorganic, organic nitrogen sources and amino acids on the coenzyme Q∧10 production and coenzyme Q∧10 component ratio was investigated. Among the nine organic nitrogen sources, CSP showed a remarkable enhancing effect on the production of coenzyme Q∧10. But this enhancement was not observed in medium containing Bacto peptone, tryptone, casamino acid and soybean meal. These differences on the production of coenzyme Q∧10 may be due to differences in kinds and amounts of component amino acids and peptides in the various organic nitrogen sources tested. In the addition of inorganic nitrogens, only (NH₄)₂SO₄ increase the coenzyme Q∧10 production by 2.0 times compare to the control group. The addition of L-tyrosine to the medium containing Bacto tryptone, was also determined to be crucial for the coenzyme Q∧10 production. But phenylalanin and tryptophan, other aromatic amino acids, had no stimulatory effect on the coenzyme Q∧10 production. These results show that the production and components ratio of coenzyme Q∧10 was greatly affected by the kinds and the concentration of inorganic, organic nitrogen sources as well as amino acids.