Samples positive for bufotenin on silica gel G sprayed with OPT showed neither DMT nor bufotenin when the plates were sprayed with DACA. When these samples were reexamined on two-dimensional cellulose TLC, some from schizophrenic urines showed DMT. The semiquantitative data obtained by comparison. of the color of the samples with that of the standards showed levels of DMT of about 1 to 2 pg in 24-h urine collections. The identity of DMT in urine samples from two drug-free chronic schizophrenics which were positive on cellulose TLC was confirmed by GC-MS analysis of both the free base and the TMS derivative (unpublished data). Thus cellulose TLC of the tertiary amine fraction is the method of choice for the identification and semiquantitation of DMT in the routine screening of urine samples, for it provides preliminary qualitative identification so that the samples can then be run on a GC-MS system.