These studies have determined that anti-LSD is capable of neutralizing the hallucinogenic effects of LSD. Both active and passive immunization resulted in neutralization of the drug. Anti-LSD antibodies have been elicited, purified and characterized. The binding properties of the antibody for the LSD ligand have been studied. Recent efforts have concentrated on studying the mechanism whereby LSD interferes with tryptophan incorporation into de novo synthesized protein. Studies have indicated that LSD is not charged by transfer RNA. It does appear that LSD may interfere with the charging of L-tryptophan to its appropriate transfer RNA. Binding studies with ribosomes isolated from rabbit lymphoid cells indicate that one mole of LSD binds per mole of ribosome. The binding is inhibited by puromycin, indicating that these two drugs bind to the same site on the ribosome particle. To determine the nature of the binding site the binding of LSD to various poly-nucleic acids has been studied. In general the results indicate significant binding to LSD to poly-purine homopolymers. These studies are being correlated to the mechanism by which LSD becomes incorporated covalently into de novo synthesized proteins.