In the present report on assay of an enzyme derived from red blood cells capable of catalyzing the formation of DMT from Cl”-SAM, as a methyl donor, and appropriate precursor is described. We used a hemoglobin free soluble fraction of the red cell as an enzyme source. Enzyme protein was incubated with Cl*-SAM and N-methyltryptamine. Enzyme activity was low but reproducible, and over 80% of extractable radioactivity was authentic DMT product. The product of incubation was identified by chromatography and co-crystallization with authentic DMT carrier. In contrast to the above procedure, if hemoglobin rich undialysed supernate was used as the enzyme source, and Cl*-SAM in ethanol as the methyl donor, only 11% of the recovered radioactivity migrated with authentic DMT carrier and 89% was confined to the 2 methyltetrahydrobetacarboline (THBC) on TLC. In the hemoglobin rich fraction of the red cell supernate formation of THBC predominates. Formation of Cl*-formaldehyde from Cl”-SAM via methanol in the red cell and nonenzymatic condensation with indoleamine substrates followed by formation of THBC is discussed. Proof of THBC formation is presented.