Methylisoamylnitrosamine, a carcinogenic N-nitroso compound, has been formed in glucose ammonium nitrate medium containing 150 mg of isoamylamine (a primary amine) inoculated with a common fungus (Fusarium moniliforme Sheldon), to which 400 mg NaNO_2 are added after incubation for 7—8 days at 28℃. No such compound has been found in control samples without fungi or isoamylamine. This paper reports a method of experimental synthesis of the nitrosamine by F. moniliforme strains 82—01 and 83—01, using isoamylamine and NaNO_2, as well as the analysis of the compound by GC/MS and GC/TEA. Methylisoamylnitrosamine, a carcinogenic N-nitroso compound, has been formed in a glucose ammonium nitrate medium containing 150 mg of isoamylamine (a primary amine) inoculated with a common fungus (Fusarium moniliforme Sheldon), to which 400 mg NaNO 2 were added after incubation for 7- 8 days at 28 ° C. No such compound has been found in control samples without fungi or isoamylamine. This paper reports a method of experimental synthesis of the nitrosamine by F. moniliforme strain 82-01 and 83-01, using isoamylamine and NaNO_2, as well as the analysis of the compound by GC / MS and GC / TEA.