The chromosome of Fusarium species during the vegetatve nuclear divisions in hyphae were observed by use of HCl-Giemsa technique on light microscope. The haploid chromosome number of Fusarium anthophilum 7472 was n=7, n=6 in F. anthophilum 7481 and n=6 in F. oxysporum 7500. The haploid chromosome number was 7 in F. napiforme 6129 and F. napiforme 6144. Those of F. caucasicum F. caucasicum ATCC 18791 and F. aquaeductuum ATCC 15612 were n=5. F. coeruleum ATCC 20088 was n=6, n=8 in F. camptoceras ATCC 16065 and n=7 in F. sambucinum NRRL 13451. From these results and previous papers, it may be concluded that the basic haploid chromosome number of the genus Fusarium is n=4.