This proposal would evaluate in depth the mutagenic potential of 9-Tetrahydro-Cannabinol in mammals. The host-mediated assay, dominant lethal test, in vivo cytogenetic analysis, as well as direct translocation procedures will be performed. Multiple doses will be used and the studies will be carried out in rats and mice. In a separate phase of this proposal, cytogenetic analysis will be carried out in male rhesus monkeys.