Four new fumonisins, an isomer of fumonisin C1 (iso-FC1) (1) and three N-acetyl derivatives of hydroxylated fumonisin C1 (OH-FC1) (2), fumonisin C1 (FC1) (3), and iso-FC1 (4) were isolated from wheat cultures of Fusarium oxysporum. One of the hydroxy groups of compound 1 is at C-3 instead of C-4 for FC1. Compounds 2-4 are similar in structure to OH-FC1, FC1, and iso-FC1, respectively, except for the presence of an acetyl group at the amine of C-1.