Biochemical markers are crucial to the development of early diagnosis of infantile autism. The blood concentrations of neuroanalytes epinephrine, norepinephrine, dopamine, and serotonin were elevated in autistic subjects (n = 13) as compared to normal controls (n = 10). Autistic subjects had peptide patterns (peaks I-V, Sephadex G-25) that were different from those of normal controls. Methionine-enkephalin has been tentatively identified from fraction I of autistic subjects by HPLC as one of a large number of peptides that appears to be elevated. The HPLC chromatographic patterns of fraction V from all autistic subjects show a peak with retention time of 7.6 min. The HPLC of control urine fraction V revealed no comparable peaks.