Twenty-five isolates of F. acuminatum, 38 of F. avenaceum, 1 of F. culmorum, 31 of F. oxysporum and 56 of F. sambucinum were obtained in 1983, 1984 and 1986 from cereal grains and soil from various parts of Norway. The isolates were grown on an autoclaved Uncle Ben's parboiled rice medium and examined for production of trichothecenes and other toxins and for toxicity in rat feeding tests. F. culmorum N46C(2) and Fusarium sambucimum 45-86-A produced zearalenone (F-2) 864 and 665 ppm, respectively and caused uterine enlargement in rats. Most of these isolates produced no known trichothecene mycotoxins that could account for the toxicity that was demonstrated in the rat feeding tests. All but F. avenaceum N26B produced fusarin C (1.5 ppm) but caused no toxic effects in rat feeding test. None of the isolates produced fusarochromanone (TDP-1). Thirteen isolates of F. acuminatum, 16 of F. avenaceum, 14 of F. oxysporum and 3 of F. sambucinum produced a cytotoxic factor which we named HM-8. One isolate of F. avenaceum, 12 of F. oxysporum and 46 of F. sambucinum produced a hemorrhagic factor which we named H-1 (wortmannin). Twenty isolates of F. acuminatum, 22 of F. avenaceum, 17 of F. oxysporum and 1 of F. sambucinum produced moniliformin. Four isolates of F. acuminatum, 9 of F. avenaceum, 25 of F. oxysporum and 52 of F. sambucinum caused death to rats. Three isolates of F. avenaceum, 19 of F. oxysporum and 47 of F. sambucinum induced hemorrhage in various organs. All isolates caused decreased weight gain, relative to the control diets.