The role of harmane, aβ‐carboline formed during pyrolysis of tryptophan, on the metabolism of AFB1, growth and some parameters of the nutritional status was investigated in the rat. Male and female Wistar rats were fed a semi‐synthetic diet containing AFB1(2 ppm), harmane (250 ppm) or both compounds, for 33 days after weaning. Qualitative and quantitative differences in the urinary and faecal excretion of parental compound and metabolites were assessed by HPLC analysis.