Twelve growing Swine were fed an 18% protein diet (Maize and Soja bean) for one hundred days containing either 0,6% sulfur amino acids (basal diet) or 0,6% and 1% DL-methionine added to the control diet. Such an excess, reduced food intake and body weight gain mainly during the "finishing period" (60 to 100 kg). The RNA/DNA and protein/DNA ratios in the muscle did not show any difference. Hepatic activities of some enzymes involved in glycolysis, gluconeogenesis and amino acid metabolism, were unchanged, except that of methionine adenosyl transferase, the first step of transsulfuration, which was induced in proportion with the amount of the methionine ingested. Swine seemed to adapt to the excessive methionine intake, which did not show any toxicity in our experimental conditions.