The N,N-dimethyltryptamines: N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-0Me-DMT) and 5-hydroxy-dimethyltryptamine (bufotenin) were completely derivatized to trimethylsilyl (TMS) derivatives with the TMS substituent on the indolic nitrogen. The GLC data of the derivatives and the MS data of combined GC-MS analysis are described. The secondary amines N-methyltryptamine (NMT) and N-methylserotonin (NMS) gave more than one derivative but in the reaction indolic NH was found to be more reactive than the secondary amino NH. Primary amines reacted with CS 2 to give isothiocyanates which have good GC properties and are ideally suited for GC-MS studies.