Amine metabolites and cortisol were measured in four consecutive 3 ml samples of lumbar cerebrospinal fluid (CSF). There were pronounced concentration gradients for both 5-hydroxyindoleacetic acid and homovanillic acid, and there was no difference in the gradients of 11 controls and 17 psychiatric patients (10 depressed). As there was a close correlation between the mean of the first two fractions and the mean of all four fractions, a concentration obtained in 6 ml can be used to calculate that in a 12 ml CSF sample. In psychiatric patients there was a slight, but statistically significant concentration gradient for 3-methoxy-4-hydroxyphenylglycol (unconjugated as well as conjugated). No gradient was found for cortisol in CSF.