Bile acids were determined in the serum and urine of four non-jaundiced patients with secondary liver tumours by means of gas-liquid chromatography. In serum only the concentration of cholic and chenodeoxycholic acids were increased in two of the patients. The renal excretion of cholic and/or chenodeoxycholic acids was increased in all patients, whereas the excretion of hyocholic acid was increased in two. The renal excretion of 3 beta-hydroxy-5-cholenic acid was not increased in any of of the patients. One patient with multiple liver metastases was studied during the development of jaundice. During this period there was an increase of serum concentrations and renal excretion both of unsulphated cholic, hyocholic, and chenodeoxycholic acids and of sulphated chenodeoxycholic and 3 beta-hydroxy-5-cholenic acids. One non-jaundiced patient with a primary liver tumour, a hepatocarcinoma, had almost normal serum concentrations and renal excretion of bile acids.